FLUENT - Science topic

good morning Mr. Jafar Behtarinik

Thank you for your feedback....i will try this.

thank you again.

Sorry not familiar with udf profile writting. Hence, I cannot help :(

Farnaz Hosseini i already try k-epsilon, PISO method, pressure based solver

Please send me link for tutorials or examples....

ANSYS fluent is used for propeller simulation

You are welcome sir

I'm available for any collaborative workflow

Use wind tunnel, could find in mechanical engineering laboratory …..

Usually, temperature overshoots with radiation occur in skewed cells. Even if there is only one, then it propagates to the surrounding cells. So, maybe you can try to locally improve the mesh quality in the parts where this overshoot occurs.

Additionally, if it is not the case, ensuring that the angular discretization of the DO model is high enough (Theta and Phi divisions >= 3) could also help.

Farnaz Hosseini thank you madame for your interaction

This is what i thought too, can you describe the steps to calculate the parameters needed to calculate the nusselt.

There's two temperatures: the wall temperature and the mean(or mixing) temperature, i wanna make sure what i did is correct(i used the report definitions option to do this).

There's something confusing me: to calculate the nusselt number we need the heat flux exchanged betweeen the wall and the fluid can you tell me how to calculate it in fluent cuz i'm not sure about what i did.

Thank you again for your feedback madame.

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.

BAD VERSIONs AT 2019, 2020.so many BUG need to solve............

Ok, thanks for the suggestion. Vivek Saxena

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

Thank you for your answer,

If I use a PRESTO and second order to solve pressure , Momentum and energy equation with simple algorithm for velocity-pressure copling. How i can set up the underrelaxation factor?

Hi, I agree with Mohammad Rahjoo , did you check that at the outlet the Backflow Direction is set to "From Neighboring Cell" instead of the (old) default "Normal to Boundary"?

Which value is specified for the Backflow Temperature?

<patchName>

{

type fanPressure;

file "fanCurve";

outOfBounds clamp;

direction in; // in | out

p0 uniform 0;

value uniform 0;

// Optional entries

U U;

phi phi;

}

Francesca Folesani (1). In the main FLUENT window, on the left side under Results, Reports-Surface Integrals-Set Up. Set Report Type as Area-Weighted Average. Field Variable should be Pressure and Static Pressure by default, so leave those settings alone. Select both inlet and outlet under Surfaces, and Compute. The results are written to the main FLUENT window.

(2). Record the inlet and outlet pressures – these are gauge pressures averaged across the inlet and outlet faces, respectively.

Note: The outlet gauge pressure should be zero or nearly zero since we had specified (by default) the outlet boundary condition as zero-gauge pressure.

(3). Close the Surface Integrals window.

If you get any solution plz share with me too.

I am interested to work with you. Currently working in in the of Material science and Nanotechnology at Chinese Academy of Sciences. Feel free to contact me.

Is this boundary condition correct for this simulation?

Thank you for your interest! We have already found the candidate :-)

Hello Raaid Allam Sir, Greetings!

Is this error resolved?

I am also getting the same error. If your problem is fixed, kindly guide me in this regard and

Kindly mail me the possible ways to resolve this error,

My email id is [email protected]

Looking forward to hearing from you.

I realdy did not undestand the question... but for whom read this after: some possibilies to post processing.

Tecplot are able to generate streamlines in 1, 2 or 3D velocity fields, all it will depends uopn from them are released. You can choose... there are at least fivr option do it. Under Analuzee TAB there is an option to generate particle paths amd streaklines.

On both you can inform the particle, radius, mass, initial velocity, drag coeficient and gravity acceleration modulus and direction.

For Particle path, if the particles have no mass, no gravity and drag are null, the result it will be the same as streamlines (they are generates as a MESH, you need turnon mesh viwe to see them) - if you have a unsteady flow ( changes on stremlines), I think the tecplot will calculate the trajectories from initial to end time. And Streakilines are transient in this conception, and the result are the same for particle paths but you can animate them! It is a lagrangeam post processing with one way coupling.

All them work from any dimension 2or 3D, steady or unsteady

CFD post, works for 3D always, even a 2D case is loaded - CFD Post was CFX Post in the past, and ANSYS CFX is alway 3D. There is some translation from FLUENT data do CDF-post, and a slim 3D geometry is created from 2D Fluent DATA. But you have a real 3D case genetare surface or volumetric Streamlines from where you want a plane, from point, lines, or any geometry entity you have created.

Particles trajectories are load as a other data file - Fluent and CFX generate this files and they need to be loaded after the case. This avoid crashes for a large numer of particles.

Oh, and there is ENSIGHT (CEI now ANSYS) - there is the same Tecplot approach.

Hello, I'm doing the similar research. I think that it can be solved by ANSYS Fluent. May be we can discuss the question.

IronPython console can be used for adding expressions in ANSYS Fluent.

Velocity is defined as displacement over time. There are various expressions of this like dx/dt from calculus. If it is one-dimensional then you don't need root-of-sum-of-squares position (RSS of x, y & z positions) to determine displacement, it is simply X2 - X1, or the difference between final position (2) with respect to initial position (1). So you need some coordinate system for your dynamics problem. 1st rule of dynamics, always define your coordinate system. 2nd rule, develop a Free Body Diagram (FBD) of the object (or entity) in question as it resides within your coordinate system. The FBD must identify ALL externally applied forces acting upon the object/entity. Then you apply Newton's second law to the FBD, F=mA, where F is the summation of applied forces, m is mass and A is resultant acceleration. F and A are vector quantities, m is scalar mass (magnitude only, no direction). Choice of coordinate systems can simplify or overly-complicate the resulting equations. If you define the coordinate origin to be the initial position, it may simplify your governing equation. All of these considerations should be applied before any application of complex modeling tools such as ANSYS, in order to estimate an expected result and recognize unexpected results that need further explanation. Conceptual modeling must come before numeric, to avoid the risk of the common "garbage-in-garbage-out" scenario. The plate speed shouldn't exceed the particle speed of the wave, otherwise your model probably has violation of the laws of conservation in one form or another. Further, if your plate is 'unrestrained' or 'unconstrained', it will give you one answer, but if you try to extract work from it by making it push on a piston or or some other form of mechanical energy conversion for power extraction/generation, that restraint or constraint or impedance will reduce the resultant deflection of the plate. The force acting on the plate over the deflected distance form the product of work (W = F times D all in the same parallel or linear direction or degree of freedom). This product gives a theoretical maximum of the possible energy that may be extracted. Your actuator (piston or generator, whatever it is) will have a conversion efficiency less than unity (<100%) which must be applied in your considerations of power generating capacity. Power is work per time or dW/dt. Be mindful of dimensional units to check for dimensional correctness of any governing equations you derive while assessing the FBD, otherwise you will fall into the "garbage-in-..." trap.

First of all, you need to decide which modes should be included in your simulation, for example, convection, radiation, or all modes.

If you are interested in knowing the convection, for example, your simulation will give you the value of h, and based on it, you can calculate the convection.

Similarly, in radiation, you will need to know the (e) and so on.

Good luck

Good evening sir V. Antony Aroul Raj Mateo Kirincic .

Sir, I am working on a latent heat thermal storage system, and trying to validate an experimental paper.

Based on your above discussion, I am trying with the variable Cp method in fluent. But still in simulation, the melting rate is much more than the experimental one.

With due respect, can you suggest something?

Is it possible to use a udf for variable-specific heat with a rectangular profile?

Regards

Prakash Singh

I also encountered this problem. Have you solved this problem? Or is there any way to avoid the adverse consequences of this warning?

Yes, kindly check out the attached picture for the mesh details.

Thank you.

Certainly! A person who is eloquent in more than one language is more likely to code-switch and mix up words from different languages within her L1. Language users be it consciously or unconsciously, seek facilitating things for themselves. Reasons for this interference vary:

1/ Similarities in pronunciation, grammar, vocabulary among languages systems like French, English, Spanish do play an important role in a multilingual society. The fact of knowing more than one language because of historical reasons, mixing up words become crucial when people communicate with others from different languages. A person who is fluent in French may easily mix up words when using English. The same thing happens to learners who mix up words from French when writing in or speaking English.

2/Language dominance: A bilingual speaker who uses the second language the whole day at work and with colleagues may not prevent herself from mixing up words when using her mother tongue at home.

3/ Prestige is another reason why people mix up words. For example, in Algeria people who uses French (a second language) words or sentences with Arabic is considered intellectual.

3/Actually languages interferences and code-witching occur even in the same language. For instance, a person who lives or works in an area which is far from home may be noticed since she uses different vocabulary and body language. The same thing happens to the same language user when words are mixed up using her own language at home.

please be sure that the physical model you defined particularly at tht interface of the boundaries are correct.

Sure, the focus study helps to find many special points of Strength in the language.

In ANSYS Fluent, resolve deforming mesh and zone definition issues by ensuring a proper setup. First, verify the mesh suitability for deformation, especially in relevant regions. Activate the deforming mesh option in the solution setup, specifying the correct deformation model. Clearly define zones, specifying deforming and stationary areas and ensuring proper connections. Set appropriate boundary conditions, paying attention to motion for moving or rotating boundaries. Check solver settings related to dynamic mesh and deformation, ensuring compatibility. Provide accurate initial conditions for deforming zones, including velocities and temperatures. Use Fluent's monitoring tools to visualize mesh deformation during simulation, aiding in issue identification. Careful review and consistency in zone definitions, boundary conditions, and solver settings are essential for a successful simulation.

It seems like you're facing a discrepancy between the strain rate contour obtained directly from Fluent and the one calculated using the expression (dV/dx + dU/dy). This could be due to various reasons, and troubleshooting such issues often involves checking several aspects of your simulation setup and post-processing. For example, the quality of mesh, the convergence study, and the good application of BC. Vibgyor Tash

Hi

you must import your model in ansys spaceclaim and repair it, or use other file translate such as sat, step,x_t and so.

Thank you, I will look that reference up!

The relationship between someone's life success and the number of languages they are fluent in can be complex and depends on various factors, including individual goals, cultural context, and the nature of their work or personal life. Here are some ways in which language proficiency may impact a person's life success:

However, it's crucial to note that language proficiency is just one factor among many that contribute to life success. Other skills, such as leadership, adaptability, and domain-specific expertise, also play significant roles. Additionally, success is subjective and can be defined in various ways—career achievements, personal fulfillment, or contributions to society.

In summary, while language proficiency can offer unique advantages, its impact on life success is highly contextual and depends on how well it aligns with an individual's goals and the demands of their chosen path.

No individual has the mental capacity to be fluent in all languages. The number of languages spoken worldwide is incredibly vast, and each language comes with its own complexities, nuances, and cultural context. Achieving fluency in all languages would be an impossible task due to the sheer diversity and number of languages spoken around the globe.

Language fluency requires a deep understanding of grammar, vocabulary, pronunciation, and cultural nuances specific to each language. It also requires regular practice and exposure to the language in various contexts. With thousands of languages spoken across different regions, it's impractical for a single person to master them all.

Even polyglots, individuals who have a talent for learning and using multiple languages, typically focus on a limited number of languages and may not achieve complete fluency in every language they attempt to learn.

The success of a person in terms of language proficiency is usually measured by their ability to effectively communicate and interact within specific linguistic communities. Success in language learning is subjective and depends on personal goals, such as travel, business, cultural appreciation, or academic pursuits.

Language specialists, translators, interpreters, and diplomats often possess advanced language skills in multiple languages, but even they tend to specialize in a particular set of languages rather than attempting to master all languages globally.

In summary, while it's a fascinating idea, the practical challenges and limitations of language acquisition make it impossible for any individual to be truly fluent in all languages. Specialization and focus on specific languages or language families are more realistic and achievable language learning goals.

If there are two overlapping control volumes in the geometry "add frozen" will create it as two different entities. Generally, if we don't remove the overlapped control volumes it will create overlapping mesh when we generate the mesh. But "add materials" just makes everything a single entity. Please also check the "boolean" operation in Ansys on YouTube you will understand it better.

Daniel Carlos Andrade Hi, I am facing the same problem. Can you let me know how you were able to solve this problem

Desta,

I am puzzled - you seem to have answered your own question.

Are you honestly looking for help?

Do you have dynamic mesh turned on while mesh adaption is running (for eg. layers/smoothing/remeshing)? This is currently not supported.

First of all, have you started designing your fan model using Vista?

Double check your blade design please.

Yes concentration gradient can be created, fluid flow can be govern using this software

First of all these are just warnings not error messages. So u can continue and try to solve this case first and then estimate the results quality.

The short answer is yes. In a transient simulation, the values at the end of each time step is used as the initial value for the next time step. Therefore, if you don't get a converged solution at each time step, your initial value for the consecutive time step is not correct.

Besides checking the normalised residuals, you can also monitor the quantity of interest to check convergence.

Though I am not familiar with the overset mesh, I would not recommend you to use an incompatible mesh for DES and LES unless you deeply trained yourself on such methods.

1-AVSYS Fluent

Accurate, comprehensive, relatively easy modeling, different physical field models, with many solved examples, simple training, suitable customization

2-ANSYS CFX

relatively easy modeling, simple training, many solved examples,

There is an Ansys Maxwell electromagnetic simulation. You can use this software, which should be installed and coupled with Ansys.

Hi Divit Karnawat.

I'm simulating a water injection into a tank, and currently, I have the same problem. I parametrized the velocity and mass flow as a profile based on a transient table, but the temperature doesn't show this option. Did you find a solution? Please, I hope your answer.

Best Regards

In ANSYS Fluent, you can obtain forces on specific surfaces using the surface integrals option. Here's a general guide:

1. **Define the Surface:**

- In Fluent, go to the "Surface" panel.

- Select the specific ISO surface you created on the blade span wise direction.

2. **Calculate Forces:**

- After defining the surface, go to the "Reports" panel.

- Choose "Surface Integrals."

- In "Surface Integrals," select "Forces" and specify the direction (span wise direction in your case).

3. **View Results:**

- Fluent will calculate the forces on the specified surface.

- You can view the results in the console or export them for further analysis.

If you're using CFD-Post for post-processing:

1. **Load Data:**

- Open CFD-Post and load your Fluent results.

2. **Define Region:**

- In the "Regions" panel, select the specific surface (ISO surface on the blade).

3. **Create Report:**

- Go to the "Reports" panel and choose "Force..."

- Define the force direction and area-weighted average if needed.

4. **Generate Report:**

- Click "Generate Report" to obtain the forces on the specified ISO surface.

Ensure that your simulation setup includes the necessary boundary conditions for accurate force calculations. If you encounter issues, consult the ANSYS Fluent documentation or forums for detailed assistance related to your specific case.

Designing multi-element airfoils involves considering aerodynamic principles, and meshing is crucial for accurate simulations. For slat and flap cove geometry, you might want to look into parametric design tools or software like ANSYS, OpenFOAM, or similar tools. Tutorials on these platforms often cover detailed airfoil design, including slats and flaps.

For meshing, tools like ANSYS Meshing or Pointwise can be helpful. Tutorials on meshing specific to your chosen software can guide you through the process.

Consider checking resources like YouTube channels, online courses (e.g., Coursera, edX), or the official documentation of the software you're using for in-depth guidance. Always ensure the tutorials are up-to-date with the latest software versions.

Dear Maziar Gheshlaghi

Do you have any information about this?

Hope these files are helpful to you.

Hi,

you only need to collect information about Korea?

Dear Sudeep N S ,

It can be challenging for anyone to provide assistance for all your inquiries. I would kindly suggest beginning by watching some introductory videos, which can help you grasp the basic concepts. As for the specific question you've raised, I'm actively working on addressing it;

1) To set boundary conditions in Fluent: Provide a clear name and select the appropriate object in the cell zone condition. Choose the right option for BC (inlet, outlet, interface, wall).

2) When dealing with liquid properties: Access the Fluent database in the material section. Edit as needed and confirm cell zone conditions, input, and output values.

3) Regarding turbulent models, there are two options: The k-epsilon model excels in free stream regions. The k-omega model offers high accuracy in boundary layers near walls. Choose based on your specific requirements.

4) To simulate and monitor heat transfer in ANSYS Fluent:

5) For effective heat transfer simulations in ANSYS Fluent:

These steps will help ensure accuracy and efficiency in your heat transfer simulations.

I hope this answer has been helpful. If you have more questions or face challenges, feel free to ask. I'm here to assist you.

Regards,

Ekta

Hi Anurag Sharma,

Thanks for showing interest in my problem.

Could you please review the attached files and guide me in understanding the concept of the core?

Hello Bikiran Kalita ,

The problem is that your mesh and the dynamic mesh method you used are not consistent. It is complicated to explain what you should do for this structured mesh. So I suggest that you change the grid to an unstructured one and use the Smoothing+Remeshing method.

ANSYS Fluent's "REFPROP 203" error often denotes a problem with the installation or configuration of the REFPROP fluid property package. ANSYS Fluent may make use of the fluid property computation software tool REFPROP to manage complex fluid properties. Here are some actions to follow in order to fix this issue:-

1. Check License and Installation:

- Make sure you have a valid and up-to-date license for REFPROP and that it's properly installed on your system.

2. Fluent Version:

- Ensure that you are using a version of ANSYS Fluent that is compatible with your version of REFPROP. It's crucial that you use compatible software versions.

3. Fluid Material Setup:

- Verify that you have set up the fluid material properties correctly in ANSYS Fluent. This includes specifying the fluid type, temperature and pressure conditions, and any other required properties.

4. REFPROP Database:

- Ensure that you have access to the required REFPROP database files and that they are located in the proper directory. You may need to specify the path to the REFPROP database files within ANSYS Fluent.

5. Environment Variables:

- Check if the environment variables related to REFPROP are correctly set. On Windows, you might need to set the "RP_PATH" variable to the folder where the REFPROP database files are located.

6. Permissions:

- Make sure that the user running ANSYS Fluent has the necessary permissions to access the REFPROP database and files.

7. Configuring the Fluid Properties:

- Review the fluid property settings in ANSYS Fluent. Ensure that you've selected the correct fluid and property mode, and that the input values are reasonable and consistent with your simulation.

8. REFPROP Documentation:

- Consult the REFPROP documentation or user manual for detailed information on setup and troubleshooting. The documentation can help you better understand how to configure and use REFPROP with ANSYS Fluent.

- If you've followed the above steps and are still encountering the "REFPROP 203" error, consider reaching out to ANSYS support or REFPROP support for more specific assistance. They may be able to help you with the error and any issues related to your specific setup.

Hello Sir

I hope you have a great day; I recommend that to watch his channel.

saud st al jadir - YouTube

RE: nonNewtonian fluids. It's rather simple to rederive the ergun equation in laminar flow for power law fluids. Answers exist in literature.

I know I'm a little late, but nevertheless, the initial step involves copying the data into an Excel (.csv) or text file. To begin, select the "irradiance maps" option and transfer the data to an Excel file, resulting in gridwise data. However, it's essential to note that Ansys interprets flux data based on X, Y, and Z coordinates rather than a grid. Therefore, the next step entails converting the grid data into coordinates. You can accomplish this using software such as Matlab, Python, or any other suitable tool. If you require assistance with the code for this conversion, please don't hesitate to reach out to me.

Dear Doctor

Go To

"The use of a swirling flow can provide a more uniform velocity distribution and a calmer filling condition according to previous studies of both ingot and continuous casting processes of steel. However, the existing swirling flow generation methods developed in last decades all have some limitations. Firstly, the swirl blade inserted in the SEN in the continuous casting process or in the runner in the ingot casting process is difficult to manufacture. Furthermore, it results in a risk of introducing new non-metallic inclusions to the steel during casting if the quality of the swirl blade is not high. Another promising method that has widely been investigated is the electromagnetic stirring that requires a significant amount of energy. Recently, a new swirling flow generator, the TurboSwirl device, was proposed. The asymmetry geometry of the TurboSwirl can make the fluid flowing to form a rotational motion automatically. This device was first studied for ingot casting. It is located in the intersection between the horizontal runner and the vertical runner connected to the ingot mold. The swirling flow generated by the TurboSwirl device can achieve a much calmer filling of the liquid steel compared to the conventional setup and also to the swirling flow generated by the swirl blade method. Higher wall shear stresses were predicted by computational fluid dynamics (CFD) simulation in the TurboSwirl setup, compared to the conventional setup. In this work, the convergent nozzle was studied with different angles to change the swirling flow pattern. It was found that the maximum wall shear stress can be reduced by changing the convergent angle between 40º and 60º to obtain a higher swirl intensity. Also, a lower maximum axial velocity can be obtained with a smaller convergent angle. Furthermore, the maximum axial velocity and wall shear stress can also be affected by moving the location of the vertical runner and the convergent nozzle. A water model experiment was carried out to verify the simulation results of the effect of the convergent angle on the swirling flow pattern. The intensive swirling flow and the shape of the air-core vortex in the water model experiment could only be accurately simulated by using the Reynolds Stress Model (RSM). The simulation results were also validated by the measured radial velocity in the vertical runner with the help of the ultrasonic velocity profiler (UVP). The TurboSwirl device was further applied to the design of the submerged entry nozzle (SEN) in the billet continuous casting process. The TurboSwirl was reversed and connected to a traditional SEN to generate the swirling flow for the numerical simulations and the water model experiments. The periodic characteristic of the swirling flow and asymmetry flow pattern were observed in both the simulated and measured results. The detached eddy simulation (DES) turbulence model was used to catch the time-dependent flow pattern and the predicted results agree well with measured axial and tangential velocities. This new design of the SEN with the reverse TurboSwirl could provide an almost equivalent strength of the swirling flow generated by an electromagnetic swirling flow generator. It can also reduce the downward axial velocities in the center of the SEN outlet and obtain a more calm meniscus and internal flow in the mold. Furthermore, a divergent nozzle was used to replace the bottom straight part of the SEN. This new divergent reverse TurboSwirl nozzle (DRTSN) could result in a more beneficial flow pattern in the mold compared to the straight nozzle. The swirl number is increased by 40% at the SEN outlet with the DRTSN compared to when using the straight nozzle. The enhanced swirling flow help the liquid steel to generate an active flow below the meniscus and to lower the downwards axial velocity with a calmer flow field in the mold. The results also show that the swirl intensity in the SEN is independent of the casting speed. A lower casting speed is more desired due to a lower maximum wall shear stress. An elbow was used to connect the reverse TurboSwirl and the tundish outlet to finalize the implementation of the reverse TurboSwirl in the continuous casting process. A longer horizontal runner could lead to a more symmetrical flow pattern in the SEN and the mold."

Dear Doctor

"Velocity inlet boundary conditions are used to define the flow velocity, along with all relevant scalar properties of the flow, at flow inlets. In this case, the total (or stagnation) pressure is not fixed but will rise (in response to the computed static pressure) to whatever value is necessary to provide the prescribed velocity distribution.

This boundary condition is intended for incompressible flows, and its use in compressible flows will lead to a nonphysical result because it allows stagnation conditions to float to any level. You should also be careful not to place a velocity inlet too close to a solid obstruction, since this could cause the inflow stagnation properties to become highly non-uniform.

In special instances, a velocity inlet may be used in ANSYS FLUENT to define the flow velocity at flow exits. (The scalar inputs are not used in such cases.) In such cases you must ensure that overall continuity is maintained in the domain.

Sometimes a velocity inlet boundary is used where flow exits the physical domain. This approach might be used, for example, when the flow rate through one exit of the domain is known or is to be imposed on the model.

In such cases you must ensure that overall continuity is maintained in the domain.

In the pressure-based solver, when flow exits the domain through a velocity inlet boundary ANSYS FLUENT uses the boundary condition value for the velocity component normal to the exit flow area. It does not use any other boundary conditions that you have input. Instead, all flow conditions except the normal velocity component are assumed to be those of the upstream cell.

In the density-based solver, if the flow exits the domain at any face on the boundary, that face will be treated as a pressure outlet with the pressure prescribed in the Outflow Gauge Pressure field.

Density at the inlet plane is either constant or calculated as a function of temperature, pressure, and/or species mass/mole fractions, where the mass or mole fractions are the values you entered as an inlet condition."

Xinke Shao Thanks for sharing, will try it later.

Subham Pal, To determine the heat flux across a point at the interface, you can use the Report > Probe Data feature in Ansys Fluent or the Probe feature in CFD post. However, if you are using a VOF model, the heat flux at the interface may be undefined at some points. This is because the VOF interface is a sharp interface and the heat flux across a sharp interface is not defined.

Hatem Ksibi Dr. Ksibi, thank you for your interest in the project. However, I am not doing things related to particle size and morphology. My project is in the realm of social science so it's relatively distant from your specialties. Thank you very much!

have you got the answer

Hello,

if you're looking for a steady-state solution, you should/could maybe also monitor and check that the input mass flow rate (total or why not H2 MFR) entering your computation domain is the same that the mass flow rate exiting the domain (on output boundaries). Maybe more iterations are needed to reach steady state in your case. As previously answered, it can be needed to change the mesh or the BC types to obtain the desired converging results... It's a bit hard to tell more without knowing the exact configuration...

Best regards

*📷* and📷Joel Guerrero

Department of Civil, Chemical and Environmental Engineering (DICCA), University of Genoa, 16145 Genoa, Italy

*

Authors to whom correspondence should be addressed.

Fluids 2021, 6(12), 462; https://doi.org/10.3390/fluids6120462

Received: 9 November 2021/ Revised: 29 November 2021/ Accepted: 29 November 2021/ Published: 17 December 2021

(This article belongs to the Special Issue Advances in Numerical Methods for Computational Fluid Dynamics With Open-Source Software)

Versions NotesDownloadBrowse Figures

Abstract Hereafter, we used the Algebraic Flame Surface Wrinkling (AFSW) model to conduct numerical simulations of the Paul Scherrer Institute (PSI) high-pressure, turbulent premixed Bunsen flame experiments. We implemented the AFSW model in OpenFOAM and in Ansys Fluent, and we compared the outcome of both solvers against the experimental results. We also highlight the differences between both solvers. All the simulations were performed using a two-dimensional axisymmetric model with the standard 𝑘−𝜖

turbulence model with wall functions. Two different fuel/air mixtures were studied, namely, a 100%𝐶𝐻4 volumetric ratio and a 60%𝐶𝐻4+ 40%𝐻2

volumetric ratio. The thermophysical and transport properties of the mixture were calculated as a function of temperature using the library Cantera (open-source suite of tools for problems involving chemical kinetics, thermodynamics, and transport processes), together with the GRI-Mech 3.0 chemical mechanism. It was found that the outcome of the AFSW model implemented in both solvers was in good agreement with the experimental results, quantitatively and qualitatively speaking. Further assessment of the results showed that, as much as the chemistry, the turbulence model and turbulent boundary/initial conditions significantly impact the flame shape and height.CFD; premixed combustion; OpenFOAM; Ansys Fluent; XiFoam; AFSW; turbulence modeling; flame speedKeywords:

1. Introduction The study of premixed turbulent combustion is an area of active research as mastering this technology can directly translate into increased efficiency and reduced NOx and other pollutant emissions. However, modeling premixed combustion phenomena is a non-trivial task because of the interaction between turbulence and chemical reactions. To overcome this challenge, many combustion models have been developed and tested, to name a few, the eddy breakup model [1], turbulent flame speed closure [2], the eddy dissipation concept [3], the coherent flamelet model [4], the extended coherent flamelet model [5], the level set approach for corrugated flamelet regimes (G-equation models) [6,7], and the algebraic flame surface wrinkling model [8].In this study, we performed numerical simulations of the PSI’s high-pressure, turbulent premixed Bunsen 𝐶𝐻4

/𝐻2

/air flame experiments [9,10]. The combustion process was modeled using the Algebraic Flame Surface Wrinkling (AFSW) model [8,11]. The AFSW model is an algebraic model originally derived by Muppala et al. [8] through curve fitting of the Kobayashi experiments on turbulent flame speed measurements for methane and propane flames [12]. The model was further improved by Dinkelacker et al. [11], where the authors included an effective Lewis number term to extend its applicability to blended hydrogen mixtures. This model has been validated for Bunsen-like flames and sudden expansion dump combustors [11,13,14], where good agreement has been obtained in terms of flame lengths and speeds.

Hereafter, we aimed at reproducing the results of Dinkelacker et al. [11] by using the open-source numerical library OpenFOAM [15,16] and the commercial CFD solver Ansys Fluent [17]. As this AFSW model is not readily available in OpenFOAM or Ansys Fluent, we implemented the AFSW model in both CFD solvers. In OpenFOAM, the AFSW model was implemented by modifying the solver XiFoam. In Ansys Fluent, the model was implemented using User-Defined Function (UDF). We then compared the outcome of both solvers against the experimental results. All the simulations were performed using a two-dimensional axisymmetric model with the standard 𝑘−𝜖

RANS turbulence model with wall functions [18,19].The remainder of the manuscript is organized as follows. In Section 2, we review the theoretical background of premixed combustion modeling, energy equation treatment, and the calculation of the thermophysical and transport properties. In Section 3, we address the implementation details of the AFSW model in OpenFOAM. The experimental setup is briefly addressed in Section 4, and in Section 5, we cover the numerical background. Section 6 is dedicated to the discussion of the results. Finally, in Section 7, we outline the conclusions and perspectives.

2. Theoretical Background 2.1. Premixed Combustion Model Under the assumption of simple one-step chemistry with the unity Lewis number and adiabatic conditions, the species transport equations can be reduced to a single combustion progress variable equation, as follows [2,20,21],

Surendra Singh Rathore Surendra Singh Rathore sir thank you for reply, I tried with all algorithms.it is working only in coupled. In remaining all algorithms, getting the same result only difference is the number of iterations it is stuck(No response why ? ). I tried relaxation factor in all quantities as u said. Now am looking for other alternatives in coupled algorithm. because in this algorithm alteast iteration process is running.

Thanks

T.Saravanakumar