Pressure - Science topic

When pressure is applied to a material, it experiences stress and tends to deform. The elastic constants determine how much deformation occurs. If the pressure is increased, the stress on the material also increases, which can lead to an increase in the elastic constants. This is because the material is trying to resist the deformation caused by the increased pressure.

The value of C11 reaching 570 GPa in your simulation indicates a high resistance to deformation along the crystallographic axes. Whether this increase is normal or not depends on the specific material and the conditions under which the pressure is applied. Some materials have higher elastic constants than others, and the elastic constants can also vary with temperature and other environmental factors.

To determine if the increase in C11 in your simulation is normal, it would be helpful to compare your results with experimental data for the same material under similar conditions. If your results are consistent with the experimental data, then the increase in C11 is likely normal. If not, there may be an issue with the simulation.

The lowest recorded air pressure on Earth that we can be sure of was measured at sea level and not inside a tornado. This measurement was incredibly low, at only 870 millibars (mb), which is 25.69 inches of mercury. This record was set on October 12, 1979, during Typhoon Tip in the western Pacific Ocean.

There is some debate about an even lower pressure being measured in a different typhoon, but that value hasn't been officially verified.

As for uneven heating of land and water in winter, that's a big contributor to lower winter precipitation in many places. Here's why:

Venkata Satyanarayana Initial temperature is 300K. The result of curve should be come in the range of 200k and pressure 0.6 mpa. If no issue, can we talk through a proper social media. I am thankful if you help me in this matter. your guidance important to me.

Sakarie Mustafe Hidig

Yes you are right and thank you for your understanding. It was about 1987 and in my early 20s. At that time I was student of Shiraz teacher training collage. There we had a psychology professor a Mr. "Mansour Owji" (1937-2021). He was also a well-known poet. In one of his classes, he talked about one of his published books that had been stolen (plagiarized) completely and published cover to cover with other names as authors. It came to me very strange, why people do plagiarize? why they themselves don't write books? and more questions. I can remember that I asked Mr. Owji some questions about that matter and as a source of curiosity I tried to understand, read and learn more about the nature of plagiarization. So my journey about understanding the nature of research and any thing surrounding it started then.

Some times honest researchers recognize the importance of what I share, but they want to collaborate for publishing books and articles, while what I have in mind is way too far bigger than just publishing some books and articles. In part for example From launching a TV or TVs dedicated to programs on "real research and science" to launching BA and MA on Science of Research" in universities, from related courses dedicated to understanding of children to courses for adults and those who go to public libraries, also Research journalism, scientometric journalism, to name just a few.

For every question to pass and transit to a new world of "real research" I have answers. But you know it is like "to rack a boat"... so maybe people in the world of academia don't like and don't want these things and changes.

To be concise, if any recognized university or higher education system around the world want to know more, I am willing to share, what I know and what could be done practically.

Check and clean your vacuum sensors may be useful

The uneven heating of the Earth's surface affects the movement of air between pressure systems and produces wind through the following processes:

In summary, uneven heating of the Earth's surface leads to the formation of pressure systems (highs and lows) and temperature gradients, which in turn drive the movement of air and the production of wind as air flows from areas of high pressure to areas of low pressure. This process plays a fundamental role in shaping global wind patterns and atmospheric circulation.

Please show the pressure reading on the y-axis. What conditions were used for the purification? Was it a gradient elution?

Thank you sir for your response....

I have one other query...

how to create Lysmer – Kuhlemeyer’s viscous boundary in Abaqus software for foundation?

Please help me out...

The ventilator in PSV mode supports the patient's breathing by detecting the initiation of inhalation, then quickly providing a supportive, positive pressure that makes it easier for the patient to take a breath. The ventilator maintains this pressure during the inspiratory phase until the set parameters for switching to exhalation are met. This system reduces the work of breathing for patients who can breathe spontaneously but need assistance due to respiratory muscle weakness or other issues affecting their breathing.

Dr Himanshu Tiwari thank you for your contribution to the discussion

I have obtained the Supplemental Material for the contribution “Pressure-Induced Sublattic Disordering in SnO2: Invasive Selective Percolation” from the corresponding author, Prof. Denis Machon. Many thanks!

1 bar = 1.4393262e-05 kcal/(mol angstrom^3)

electron beam welding provision is there or not in comsol multiphysics

thank you for sharing your valuable thoughts and data.

From the second law of thermodynamics in an reversible process one has:

TdS=dU+p dV

where S is the entropy, T is the absolute temperature (in K), p the pressure and V the volume. For an ideal gas p=R T/V where R is the ideal gas constant. For an ideal gas the internal energy is only a function of temperature hence dU =Cv dT, where Cv is the specific heat at constant temperature. Also for an ideal gas R=Cp-Cv where Cp is the specific heat at constant pressure. Hence the second law of thermodynamics combined with the first law becomes:

dS/Cv=(dT/T)+ (R/Cv)(dV/V)

For an isothermal process dT=0 so that a compression dV/V<0 implies a reduction of entropy. For a gas with constant Cv one can furthermore write:

(S-So)/Cv=ln(T/To)+(R/Cv)ln(V/Vo)

and

R/Cv=gamma-1

Hello Nitish Palanna ,

All you need to do is set the operating pressure to 0 and enter absolute pressure values for the boundary conditions.

Kind regards

Ashkan

Interestingly enough, I have the same problem but with another model of Brooks thermal mass flow controller.

The only way I could completely stop the gas flow is by closing the valve before the controller.

Also, to be fair, Brooks specifies in the manual that the controller readings can be trusted only when the gas flow rate is bigger than 10% of the set point mass flow rate.

Normally, if the column used has been properly equilibrated and an observed gradual increase of pressure "over-normal" continues run-to-run, this indicates one of two things: (1) That Column fouling is taking place OR (2) you have a clogged HPLC pump OUTLET FRIT. Both of these errors will result in what you observe. More info follows...

Let us take a look at these two problems in a bit more detail.

(1) Column Fouling: Columns ger fouled with sample over time. This may be from overloading the column with sample (use less sample!) or from improper column washing. Make sure you wash the column down with a solution that is stronger than the mobile phase used for the analysis. In your example using MeOH and water ("5 mM Ammonium acetate in a 1% acetic acid solution is basically water) you will need to use a different solvent for this purpose. The wash solvent should be fully soluable with your samples and stronger than MeOH. Perhaps ACN would be best? Remember to separate your Analysis method from your column wash methods. When the analysis method is complete, the solvent composition should NOT be directed back to the starting conditions within the same method (a common newbie mistake). *We used to do this back in the early 1980's, before computers. Professional training today is different and a second 'new method' (known as "The wash method") is programmed to run after the analysis method. Create and save a "Column Wash" method where you change from MeOH in your example to ACN (which is "stronger" and will elute off different material). In this example; Flush the column with acidified water plus a max of 95% ACN. Create and save another method, a third method, that equilibrates the column in your initial analysis mobile phase (this is how the pros do it, using separate methods for each task. Makes it easy to automate the tasks). Now you should have three dedicated methods that can be called on or run sequentially to: equilibrate the column, run the analysis, wash the column, equilibrate the column .... This helps to insure all runs are washed, equilibrated and analyzed the SAME (machines are really good at this).

(2) Obstructed Pump Outlet Filter: As a professional consultant I am asked to troubleshoot many HPLC system issues where the system back-pressure slowly increases over time (days, weeks, months) and while #1 above is often to blame, there is another reason. Inside every HPLC pump is a small filter designed to catch piston seal debris and other larger particulate matter from making its way into the very narrow passages of the HPLC system, especially the injector. These very inexpensive filters are consumable parts which are designed to be replaced on a regular basis to maintain proper function. If they are not replaced, then they fill with debris resulting in a PARTIAL OBSTRUCTION of the flow path. This is observed as a slow increase in system pressure over time. It also may appear as an increase in back-pressure when directed solvent to waste (pump to waste, not to column). When directed to waste only, the expected back-pressure should be very, very low. In fact you should know what the normal pressure should be given a specific solvent and flow rate for your system. If the pressure is higher than normal, then the frit is probably overdue for replacement. Change it.

Yes, with these parameters you can calgulate the mass flow

Dr Murtadha Shukur thank you for your contribution to the discussion

Robert Adolf Brinzer Kangdi Sun after rotary evaporation is it necessary to dry film further in vaccum or flushing with nitrogen gas?

The adsorption of gases on solids depends on the activation of the solid absorbent. The adsorption capacity is measured using static or dynamic methods. The static method is based on determining the difference between the concentration of the adsorbed component in the initial solution and in the solution, which is in equilibrium with the adsorbent.The formula Qe = (C0 − Ce) × V/m was used during the test to calculate the adsorption capacity. Here, C0 and Ce are the concentrations of Sb(III) before and after the adsorption, mg L−1, respectively; V is the volume of the Sb(III) solution, mL; m is the adsorbent dosage, mg. Isothermal adsorption test.

<patchName>

{

type fanPressure;

file "fanCurve";

outOfBounds clamp;

direction in; // in | out

p0 uniform 0;

value uniform 0;

// Optional entries

U U;

phi phi;

}

Hey there Ahmad Alsuwaidi !

Your proposal sounds pretty solid! Utilizing techniques like Coat-redfern or Model Free to determine Activation Energy and pre-exponential factors is a smart move, especially for non-isothermal experiments. Once you've got those values, applying kinetics in various partial pressure studies to determine partial pressure order seems like a logical next step.

Another approach you Ahmad Alsuwaidi might consider is leveraging computational methods like Density Functional Theory (DFT) or Molecular Dynamics (MD) simulations to gain insights into the partial pressure order. These techniques can provide valuable theoretical data that complements experimental results.

Overall, your plan seems well-thought-out, but integrating computational methods could offer additional depth to your analysis. Keep up the great work Ahmad Alsuwaidi !

In fluid mechanics according to continuity equation A1 X V1 =A2 X V2 , showing velocity inversely proportional to cross sectional area , since in FM it is well known that velocity is inversely proportional to pressure, this inverse relation of velocity with area and pressure gives direct relation. As area decreases velocity increases and pressure at that point decreases. But we also know that pressure is inversely proportional to area[P=F/A]. The higher the velocity of a fluid (liquid or gas), the lower the pressure it exerts. This is called Bernoulli's Principle. Fluid pressure is caused by the random motion of the fluid molecules. Pressure equals force divided by area ( P = F A ). The equation shows that pressure is directly proportional to force, but inversely proportional to area. At a constant area, pressure increases as the magnitude of the force applied also increases. Similarly, in fluid flow, when the fluid speeds up (increases its velocity), it has less energy to exert as pressure. So, as the speed of the fluid goes up, the pressure it can exert goes down, and vice versa. As per equation of continuity, when the liquid flows through a constriction, the area of cross-section of the liquid decreases, therefore the velocity of the liquid increases. Thus, as the fluid passes through the constriction or throat, the higher speed results in lower pressure at the throat.

The length and cross-sectional area of a conductor directly influence its electrical resistance. Length is directly proportional to resistance, while cross-sectional area is inversely proportional. Speed increases when cross-sectional area decreases, and speed decreases when cross-sectional area increases. This is a consequence of the continuity equation. If the flow Q is held constant, when the area A decreases, the velocity v must increase proportionally. The area of the cross-section is inversely proportional to resistance because: Resistance inside a conductor is caused by the collision of charged particles or electrons with each other. When the area of the cross-section of the conductor is increased space between charged particles will also increase. Resistance is proportional to resistivity and length, and inversely proportional to cross sectional area. As the cross-sectional area increases, velocity decreases. Arteries and veins have smaller cross-sectional areas and the highest velocities, whereas capillaries have the most cross-sectional area and the lowest velocities. The velocity v of a fluid flowing in a conduit is inversely proportional to the cross-sectional area of the conduit. The fluid velocity increases, the pressure of the fluid decreases. Therefore, the pressure of the fluid decreases as the pipe becomes narrower. Principle of continuity av = a constant or v ∝ 1/a i.e. as the water flows from wider tube to narrow tube its velocity increases. According to Bernoullis Principle P + 1/2 ρv2 = a constant where velocity is large the pressure is less. In a stream-line flow of a liquid according to equation of continuity av = a constant where a is the area of cross-section and v is the velocity of the liquid flow. When water flowing in broader pipe enters a narrow pipe the area of cross-section of the water decreases therefore the velocity of water increases. The higher pressure in the wide part pushes on the fluid in the narrow part and accelerates that fluid. So the fluid in the narrow part starts moving faster. Now the fluid in the narrow part not only has lower pressure but also a higher speed—because it was accelerated by the higher-pressure fluid behind it. As the velocity of the flow increases, the organization increases, and the pressure drops further. The organization and density increase is a result of the fluid doing work on itself.

The principle of continuity, the principle of conservation of mass. These two principles are an important reason and an important explanation behind the fact that, when the area of flow is decreased, the velocity of flow has to increase in the same proportion for the two principles to remain valid. Incompressible fluids have to speed up when they reach a narrow constricted section in order to maintain a constant volume flow rate. This is why a narrow nozzle on a hose causes water to speed up. Since velocity is high at the narrow constriction, hence the pressure is low there. For one thing, the velocity of fluid is related to the resistance of the fluid in contact with the tube. As the cross-sectional area increases, so does the surface area of the inside of the tube, resulting in a greater resistance to flow. If the area decreases the pressure increases as given by P = F/A. But, according to Bernoulli's Principle, as the area decreases, the speed increases, and as the speed increases, the pressure decreases. The pressure on a surface is inversely proportional to the area of the surface, provided that the force applied on it remains constant. Therefore, the pressure will decrease if the area on which it is applied is increased. Additionally Flow rate and velocity are related by the equation Q = Av where A is the cross-sectional area of flow and v is its average velocity.

Rk Naresh

Imagine that you have a certain amount of particles that has to pass through an area. When you decrease this area, the same amount has to pass through it, and hence it has to increase the speed (this is a simple answer).

In the next part of the question, there is a term called total pressure, and it is conserved in the flow when there is no forces exerted. The total pressure combines two terms (dynamic pressure 0.5*rho*U*U, and static pressure P). Increasing the velocity would increase the dynamic pressure, and therefore the static pressure has to decrease to maintain the same value of total pressure.

Total Pressure Po = 0.5*rho*U*U + P

I hope this clarifies the matter.

Hello Mohammadreza Kord

Often when you increase Re, it means that U is increasing. And the non-dimensionalizing approach that you are using contains U in the denominator, so it is normal and logical that increasing the velocity would decrease the pressure.

Performing the experiments at different partial pressures will bot give you reliable kinetic parameters (triplet: activation energy, pre-exponential factor, reaction order) because kinetics (in this case) is associated to temperature. The different pressures will indeed allow the determination of the function that describes the phonomenon according to a pressure change. For the kinetic triplet, Vyazovkin teaches:

In this sense, your colleagues are right: if you want reliable kinetic parameters, you should perform additional heating rates.

I hope it helps 😄

as we know fluid pressure (p=force /area).from this formula we can relate the parameters p~1/area where as p~force .starting from this point as pressure decrease area will be increased vice versa.due to inverse relation.

Dear Long Tran

Still I am searching for reflected pressure value, I have find only incident pressure value. Can you help me?

The Ergun equation and several similar equations, predict the pressure drop through a bed of solid before fluidisation starts, i.e. flow through a packed bed. The pressure drop is then equated to the weight of the bed divided by its area at the point of fluidisation (minimum fluidising velocity).

The topic is well covered in the better texts. The practical problem is characterising the solids mean particle size for practical systems: it all works well for uniform sizes, but voidage varies widely if there is a wide particle size distribution.

Dear Jian,

Yes, It is due to the outside pressure. As the pressure is decreased, the plasma plume expands both in length and width. These expansions are stretched and built up farther from the nozzle exit. The primary reason for this expansion is the decrease in absolute pressure. As the number of surrounding molecules decreases, their collision with the species exiting the nozzle also decreases. As a result, the jet requires more distance to equilibrate pressure. When both the exit and outside pressures are equal, the jet's static pressure is in equilibrium with the surrounding pressure, and no expansions occur.

Hello,

Thank you for this discussion. In general yes for incompressible and steady flow conditions using Bernoulli’s principle. When fluid flows through a narrower section of a pipe (constriction or nozzle), the cross-sectional area decreases. According to Bernoulli’s equation, the total energy remains constant along a streamline. The fluid must speed up to maintain the same volume flow rate. The kinetic energy term must compensate for the reduced pressure energy due to the smaller cross-sectional area. So simultaneously, the pressure within the fluid decreases as it accelerates.

Static pressure refers to the pressure exerted by a fluid when it's at rest or moving at a constant velocity. So measured perpendicular to the surface of the fluid (and independent of the direction of flow). Dynamic pressure represents the pressure exerted by a fluid due to its motion. So measured parallel to the direction of flow which makes it dependent on the fluid velocity and density.

Dr Murtadha Shukur thank you for your contribution to the discussion

Dr Murtadha Shukur thank you for your contribution to the discussion

Your observations are partially correct. Here's a breakdown:

Therefore, the relationship between pressure, area, and speed depends on the specific context. Remember that Bernoulli's equation applies to incompressible fluids, steady flow, and a single streamline. In more complex situations, other factors like friction and turbulence can come into play.

Can you be more specific? Which gas are you studying? At which temperatures and pressures?

The thorax is expanded by the action of either the muscles of the rib cage or the midriff. This lowers the pressure in the thorax cavity, and the alveoles, being elastic, expand.

Dr Murtadha Shukur thank you for your contribution to the discussion

Dr Murtadha Shukur thank you for your contribution to the discussion

I'm facing the same issue. The pressure is slight above the minimum value that allow the instrument to be operative. The value of forepump pressure and the energy consumption of the turbo is minimal. Did you solve your issue? If yes, exactly what seal did you replace?

dear Engr. Tufail

I upload the inp file of ABAQUS, thank you for your help！

Hello Songcai,

I am facing the same problem, did you manage to find a way to use vectors with the function or did you just end up using a loop?

Thanks,

Caio

Hi, I am not familiarized with that specific microinjector, but in our lab we used to have the same problem with the Narisigue IM-300 microinjection. We fixed it by cleaning inside the injection holder were you insert the neddle and changing the rubber inside the holder cap. Hope it helps.

The relationship between saturation temperature and pressure for any substance is empirical by necessity. There are theoretical relationships between various properties, such as ∂h/∂s)p=T (from Maxwell's relationships) and the Clapeyron equation, dPsat/dTsat=hfg/TsatVfg. The NOVEC family of refrigerants has been identified as "green friendly" so you might want to investigate them. You need to study Thermodynamics. The greatest textbook ever written on the subject is by Gordon van Wylen and Richard Sonntag.

Just from the nice pic, I think the data different between MD and exp. is fairly closed from my point.

A small tip is that in exp. materials often consist of defects, vacancies, dislocation, grain boundaries and so on but in MD the materials is a perfect crystal in your case.

So I think you can accept this result.

And if you're not satisfied, I would like to propose two aspects which you can do furhter tests.

1. increase the number of atoms in the system. A big system would result in better results( or not).

2. chose a "good" potential. A good potential is critical to the properties of systems. Before you do further production run, a systematical tets of exsists potentials is essential.

There is often liquid in the lumen during an Esophageal manometry that does cause pressure changes, called the Intra-Bolus pressure. The impedance technology can tell us if it's liquid or air.

Generally, as the temperature of a liquid increases, its vapor pressure also increases. This is because at higher temperatures, the molecules of the liquid gain more energy and are able to break free from the surface and form a gas. As a result, the pressure of the gas above the liquid increases. The temperature in the weather condition of a place increases as the heating effect of the air pressure rises to a high level. When the molecules in the warm air become light then the warm air expands causing less force. The opposite effect takes place when the temperature level of a place decreases to a low level. The heat transfer rate regarding the cooling of the hot air is also a significant parameter. As the temperature difference between the hot and the cooled air increases, the pressure losses are also increasing. The quantitative relationship between heat transfer and temperature change contains all three factors: Q = mcΔT, where Q is the symbol for heat transfer, m is the mass of the substance, and ΔT is the change in temperature. The symbol c stands for specific heat and depends on the material and phase. Boyle's law: PV = constant (at constant T). For a low-density gas at constant volume the pressure is proportional to the temperature. Law of Gay-Lussac: P = constant * T. For a low-density gas at constant pressure the volume is proportional to the temperature. When the temperature of a sample of gas in a rigid container is increased, the pressure of the gas increases as well. The increase in kinetic energy results in the molecules of gas striking the walls of the container with more force, resulting in a greater pressure. Air pressure, however, has minimal direct influence on the rate of heat transfer through convection. Higher air pressure does affect the density and viscosity of the air. However, these effects are relatively small and have a limited impact on heat transfer.

p_int and T_int refer to your intake manifold pressure and temperature, V_cyl is the cylinder displaced volume.

The state of matter with particles having the highest energy is plasma. In this state, atoms are subjected to such extreme temperature and pressure that their electrons are stripped away, creating a gas of free-moving, highly charged ions and free electrons. These free particles possess immense kinetic energy due to their unconstrained movement and strong electrostatic repulsion.

Now, let's see how temperature and pressure impact the kinetic energy of particles in a system:

It's important to remember that both temperature and pressure interact with each other and can have complex effects on the kinetic energy of particles in a system.

Therefore, while plasma represents the state with the highest individual particle energy due to its unique structure, understanding the nuanced interplay of temperature and pressure is crucial for predicting the overall energetic behavior of a system.

You're right, kinetic energy is not directly proportional to pressure, but it relates to pressure in a specific way:

While it might seem intuitive to think they're directly proportional, the actual relationship is slightly more nuanced:

So, pressure is a combined effect of both the average kinetic energy per unit volume and the number of particles. This gives us the formula for ideal gases:

P = (N * k * T) / V

where:

Now, regarding how temperature affects the kinetic energy of particles:

Therefore, while not directly proportional, pressure and temperature are both related to the average kinetic energy of particles: temperature dictates the individual energy, while pressure considers both energy and density of particles.

I hope this clarifies the connection between kinetic energy, pressure, and temperature! Feel free to ask further questions if you want to delve deeper.

Pressure and kinetic energy in a system of particles are interrelated, but they don't directly affect each other. Here's how:

Remember, these principles primarily apply to ideal gases and may need adjustments for real-world scenarios with complex interactions or non-ideal gas behavior.

yeah, it is another way to asking. You are right, sir. You know, my theory(The theory of creativity) has limitations till 3rd dimensions . It is also working in dimensions >= 4. So, we can not sure for its limitations. Take a dimension of space, so time is a fourth dimension in a space. We can think like if we put one object like planet. Then we apply my theory on it. In space, there are many dimensions can be exist. So, there is possibility that it will go to the higher volume. Therefore, you are right sir, it can go to the higher volume. Thank you for your response sir.

Thank you for the answer. I am not in log scale. I would redifine the question to: What is the effect of other gases in the mixture (QMS) on the signal (torr) of one component from the mixture. Example: I have 5 % H2 in Ar and 5% H2 in Ar+He. The total flow is the same for both cases. Why the signal for H2 (m/z=2) is not the same for both cases? Why change of the Ar into He (without change in H2 concentration) affects the signal?

I used to measure the osmolarity for (home made) insect cell media without agarose then add agarose (low melting) to do plaque purification ... no problem

Hi,

I don't know about Abaqus. We have developed a method to implement pore pressure using a single element using XFEM. This can be useful to you.

Full article: Modeling holes and voids in three dimensions using a single element within the Extended Finite Element framework (tandfonline.com)

There is nothing like "failure" as such. The case involves action of wind on an iced conductor. That's all. I tried deriving equations by separating the effects and COV's of ice and wind but the results were disappointing.

Thank you Arkadeep Sarkar . This was really helpful.

Dear friend Amira Adel

Ah, the mysteries of chemistry! Now, let's tackle this precipitating puzzle.

Firstly, when dealing with the synthesis of CuInS2 quantum dots (qdots) capped with DHLA-PEG, the precipitation could be attributed to several factors:

1. **Reaction Kinetics:** The precipitation might be due to the kinetics of the reaction. Sometimes, the formation of nanoparticles is a complex process, and the reaction conditions need fine-tuning.

2. **Particle Size:** The size of the quantum dots could influence their stability. Larger particles might have a tendency to precipitate more than smaller, more stabilized ones.

3. **Capping Agent Interaction:** DHLA-PEG is a ligand used to cap and stabilize quantum dots. If the interaction between the capping agent and the quantum dots is not optimal, it could lead to precipitation.

4. **pH Effects:** Even with a seemingly neutral pH, certain reactions may have pH-sensitive steps. Check if any intermediary products or side reactions are pH-dependent.

5. **Contaminants:** Presence of impurities or contaminants in the reaction mixture could cause unexpected outcomes.

Here are a few steps you Amira Adel might consider:

- **Reaction Monitoring:** Regularly monitor the reaction progress using techniques like UV-Vis spectroscopy. This can provide insights into the formation and stability of the nanoparticles.

- **Capping Agent Optimization:** Experiment with different ratios of DHLA-PEG to see if you Amira Adel can find an optimal condition that minimizes precipitation.

- **Temperature Control:** Although you Amira Adel mentioned no exposure to heat, ensure that the reaction is conducted under controlled temperature conditions.

- **Post-Synthesis Treatments:** Consider post-synthesis treatments, like purification steps, to remove any unreacted or undesired products.

Remember, the devil's in the details in these reactions. It might take some experimentation to find the sweet spot for synthesizing stable CuInS2 qdots. Good luck, intrepid researcher Amira Adel!

I have to correct Ali Alnazza Alhamad . The monolayer (from which the surface area can be calculated using BET equation) is formed around 0.1 p/0, or even lower for micropore-containing samples.

The vertical rise at p/p0 ~1 has nothing to do with the sample... its simply the adsorbate condensing in the sample cell Christian Weinberger spotted that. Often comes about by incorrectly "assuming" a value for p0 and not using the correct value by having the instrument measure it. In this case, the p0 value being used by the instrument is higher than the true value. For N2/LN2 p0 is around 10 torr higher than ambient atmospheric pressure... you can do a quick sanity check on the data using that to see how much the p0 was in error.

D M NAVEEN Giri You might test it to be sure. I used a few drops of octanol in 600 ltr of water and it had a major influence on coalescence (all small, christmas ball formed bubbles). Already drops of oil may spread on the surfaces in a monomolecular layer reducing mass transfer coefficient up to a factor of 10.

I agree that it might be much more easier to measure such system. But I am afraid that this system data has not been published, but might be available in some of the companies making this compound. I was dealing a lot with measured data and physical property databases, but often found that data even for many simple and common systems was not available in open literature or databases. In company projects proceeding with speed there usually was no time for measurements and one has to rely on predictive calculations methods. Often, I wished that companies will allow to publish experimental data if they had that done, at least for cases where they do not have any need for that data due to stopped project/closed production etc. They state that the data has been expensive and time consuming to obtain, and will keep that data just for them.

Without the full details of your flow problem and numerical method is not possible to answer.

Sometime hydrogen chloride formed with reaction of the impurity of metal of tank

C2H5Cl →C2H4 + HCl

When HCl formed the corrosion also takes place

Please see a thermodynamics textbook for example the text by Kenneth Wark.

Dear friend Mohammadreza Kord

Ah, diving into the intricacies of fluid dynamics, are we? i am up for the challenge!

Given your setup of a 2D wavy channel with a time-varying pressure at the inlet, let's talk about the boundary conditions for the inlet of velocity. To ensure the velocity is dependent on the time-varying pressure, you Mohammadreza Kord might want to consider the following options:

1. **Inlet Boundary Condition - `fixedValue`:**

- Set a fixed velocity at the inlet based on your pressure equation. The velocity at the inlet would be determined by the time-varying pressure.

```cpp

inlet

{

type fixedValue;

value uniform (Ux, Uy, 0);

}

```

Here, `Ux` and `Uy` are the components of the velocity. You'll need to replace them with the expressions that relate velocity components to the pressure.

2. **Inlet Boundary Condition - `zeroGradient`:**

- If you Mohammadreza Kord want the velocity to be determined entirely by the pressure gradient without imposing a fixed velocity, you Mohammadreza Kord could use `zeroGradient` to let the solver calculate the velocity based on the pressure.

```cpp

inlet

{

type zeroGradient;

}

```

This condition allows the pressure gradient to influence the velocity at the inlet.

3. **Outlet Boundary Condition - `zeroGradient`:**

- For the outlet, setting `zeroGradient` is often reasonable to allow the flow to evolve naturally out of the domain.

```cpp

outlet

{

type zeroGradient;

}

```

Remember, the appropriateness of the boundary conditions depends on the specifics of your simulation. Experimentation and validation against known results or experimental data will help you Mohammadreza Kord refine your approach. Also, don't forget to check the solver settings, discretization schemes, and time-stepping methods for numerical stability.

Give these a try in your OpenFOAM setup and see how the fluid dance unfolds in your wavy channel!

The type of BCs depends on the chosen model, compressible or incompressible.

The incompressible flow problem is well posed if you prescribe your pressure BCs

Jarne De Vleeschauwer, I have tried to create a dummy file just to give you an idea how to do it. Replicate the procedure for your slab model or bench, whatever it is, to get the idea of working on it. Good luck !

This topic is covered in detail in most texts on fluidisation, so I'm not sure what you are asking. What is rarely covered, is the energy to unlock the packed bed: this is shown by the pressure drop exceeding the bed weight just before the bed fluidises. It is very dependent upon the shape of the particles and their properties.

The partial pressure of a gas in a solution is related to the concentration of the gas in the gas phase above the solution and its solubility in the solution. In the case of bubbling nitrogen gas containing H2S through a solution, the H2S will dissolve in the solution until an equilibrium is reached between the concentration of H2S in the gas phase and its solubility in the solution.

If you want to maintain a constant partial pressure of H2S in the solution, you would need to continue bubbling the gas to replenish any H2S that escapes from the solution into the gas phase. If you were to close the system and pressurize it, the equilibrium between the gas and the solution would shift, and the partial pressure of H2S in the gas phase would likely increase. This may cause more H2S to dissolve in the solution, leading to a higher partial pressure than the desired 0.5 kPa.

In summary, maintaining a constant partial pressure of H2S in the solution usually requires continuous bubbling to replenish the gas phase. Pressurizing the system and closing it may not achieve the desired partial pressure as it could alter the equilibrium between the gas and the solution.

If continuous bubbling is impractical for your setup, you might explore alternative methods such as using a controlled release system or a gas regulator to maintain the desired partial pressure. It's essential to consider the specific requirements of your experiment or process and consult relevant literature or experts in the field for guidance tailored to your situation.

Properly set up the temperature and pressure conditions to ensure they are applied to the workpiece. If you're encountering issues where the temperature and pressure are not being applied, here are some potential troubleshooting steps:

1. Verify material properties: Ensure that you have assigned appropriate material properties to the workpiece in DEFORM 2D. The material properties, such as thermal conductivity and specific heat, directly affect how temperature is applied and distributed in the workpiece.

2. Check boundary conditions: Review the boundary conditions you have specified for the workpiece. Make sure you have properly defined the temperature and pressure boundary conditions at the appropriate regions of the workpiece. Check that the boundary conditions are correctly assigned and activated in the simulation setup.

3. Check element types: Ensure that the elements used to mesh the workpiece are capable of incorporating temperature and pressure effects. In DEFORM 2D, elements such as "convection" or "heat transfer" elements are typically used to model thermal effects. Similarly, "pressure" or "contact" elements may be necessary to capture pressure effects. Verify that the elements used in the workpiece mesh support the desired thermal and pressure behavior.

4. Element connectivity: Double-check that the mesh connectivity is correct. Ensure that the elements are correctly connected to each other and form a coherent mesh. Inaccurate connectivity can lead to improper transfer of temperature and pressure between elements, resulting in issues with their application.

5. Review simulation settings: Review the simulation settings and parameters in DEFORM 2D. Verify that you have set up the simulation correctly, including time steps, material models, solver settings, and any specific parameters related to temperature and pressure application. Incorrect settings could prevent the appropriate application of temperature and pressure.

6. Consult DEFORM 2D documentation or support: If you have followed the above steps and are still experiencing issues, it's recommended to refer to the DEFORM 2D software documentation or contact their technical support. They can provide specific guidance and help troubleshoot the issue based on your simulation setup and the specific version of the software you are using.

Hope it helps

To Apfelbaum - In gasdynamics, there is also a generalized Bernoulli theorem which applies to compressible flows, the only assumption being that the flow must be omoenergetic, not even isoentropic.

If you're reporting gauge pressure you should include the barometric pressure at the location and time of the experiment. You can acquire an instrument or get the value from a local weather station. If you use information from a weather station, be aware that they often report STP and SLP (i.e., actual station pressure and "corrected" to sea level). Don't use the "corrected to sea level" value (SLP).

Consider adding an additional length before the current inlet of the channel you are modeling to make sure the flow has the chance to reach complete hydraulic development. In other words, you should have two inlets, an imaginary one, far before the current inlet, and another one from which your hydraulically-developed flow should start.

The distance between the imaginary inlet and the current one allows the flow to be fully developed; however, that part should be disregarded during the calculation of the results, and it is added just to reach hydraulic development.

I hope this can be helpful in your case.