ANSYS - Science topic

please dear Ankush Pratap Singh , did you find an answer to this?

good morning Mr. Jafar Behtarinik

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

thank you again.

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

thanks to you dear sir Nils Wagner .

It was the commercial 18.2 that had the error. Thanks

You are welcome sir

I'm available for any collaborative workflow

Maojin Gong This AI response is not false as it could be sufficient for a reader Lamda. However, it is not scientifically accurate as we are on a research thread. Furthermore, it does not display the mentioned references...

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

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.

In discussions regarding the appropriate Capillary Number (Ca) for ignoring capillary effects in microchannel studies, it's essential to consider the context of the interface interactions. Typically, for water flow inside silicone microchannels, many studies, including mine, use the water-air surface tension value of 0.0726 N/m. This is generally because the dominant interface under investigation is between the water and air, not between the water and the silicone walls, unless specific surface modifications of the silicone suggest otherwise.

Furthermore, concerning the critical value of Ca, while the standard threshold is often set at Ca = 1, I believe this may not be universally applicable. In my study, which investigates forced flow with Reynolds numbers between 125 and 1300, it appears that capillary effects could be non-negligible even above this threshold. This observation leads me to suggest that the traditional threshold of Ca = 1 might need adjustment based on specific experimental conditions and flow behaviors. Such an approach allows for a more nuanced understanding of when viscous forces indeed dominate over capillary forces in practical scenarios

Farshid Hesami

Thank you, Timileyin!

I tried the solution you had proposed and I received the resulting heat flow on element. So the way you pointed out works.

But now I have another problem...

Why do the sum of individual heat flows in FE's is not equal to the sum of (internal heat generation in every FE multiplied by its volume (Q = Qv_FE*V_FE)?

Hello,

I think this is a common question of all CFD engineers.

The messages you saw show a signal of "Divergence!". Why? Let me point out several possible reasons:

- Mesh: This is the most basic mistake of beginners

- Boundary conditions: Wrong or inappropriate settings. e.g. back flow with a strange temperature value. For the reactions kinetics, it is better to test them in Excel or MALAB first. Check the unit of values.

- Model settings: Most of solutions can be found here. It is better to read more papers, tutorials, and books. You need to find the suitable set of numerical methods to minimize the errors. Since errors may come from various sources, you need to trial all of them. Several problems cannot be solved by the steady state solver.

- Physical properties: At the beginning, you try to use constants. Do not mix constants and polynomials. When your system becomes more stable, you can try to turn it back to temperature dependent.

- Initial conditions: Check carefully your initial conditions. Use the interpolate file if necessary.

- Time step size: Do not reduce the under relaxation factors, reduce the time step size instead.

- Bugs of UDF: Some NaN values or divide-by-zero errors

- Simplification: Do not solve directly a complex problem. Solve a simpler one. Then you can increase the complexity.

Hello Ramiro!

Thx for answer and spending free time for this question!

Well, I used to prepare the brick model and execute actions according to your algorithm before I asked the question here. I do understand the algorithm but receive the expected result, i.e. unstable rising of brick temperature.

I applied PLANE77 elems for SS thermal analysis and PLANE183 ones for SS structural FE a ND analysis.

I used solver op's for nonlinear effects on geometry (NLGEOM, ON) and elems update (UPGEOM) after each cycle of thermomechanical iteration.

I suspect heat balance is not constant with every new thermomechanical iteration iteration. But I don't know how to receive this data out of ANSYS. Perhaps *GET command will help through SMISC op's for elems.

Sadiki Zakariae Dear Now i used 2D model of savonius wind turbine but same issue is appearing it has been convergent Fastly around 100 (i put 1000 titration )

Calculate the orthotropic stress and strain limits based on the material properties and ultimate strength or ultimate strain values you defined earlier (material properties).

If it's all done, you can use the postprocessing tools to extract the stress and strain in each direction.

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.

Yes, if the automatic solid time step is too low.

For the geometry you could alternatively intersect the fluid and solid volumes to get a single shared surface between the two volumes instead of having to define interfaces.

Of course, a radiation model should be used as well. But the solid should be heated by the bottom fluid anyway.

Hii I am researching natural fiber composites. I'm doing tensile testing and at the same time, modeling and evaluating specimens through Ansys software. I need to validate the Ansys results with the testing results. I need to know about various methods for this validation process. Where can I find accurate validation methods?

Thanks.

I have been using both for 40 years. Ansys and Nastran both started on a solid basis but Nastran had failed to develop over the years. It took hold in aircraft structures for 2D linear analysis and analysts have invested much time and effort in developing their own techniques for using it. They remain loyal to it although some are migrating to Abaqus because it has corporate approval from Dassault connections. Ansys was chosen for 3D models such as in engines. Aircraft structures largely shunned solid elements as the models became 'too large'. In the end, ANSYS has aggressively developed while NASTRAN has not. And, computing resources are now cheap enough to solve very very large models. So, you can read a large assembly of aircraft solid parts into ansys and easily get much higher accuracy faster than you will get in the reduced 2D linear models in NASTRAN.

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.

Priya Shinde Can you share your CAD model (.step or .iges)?

Hello,

Very true....I am using CST microwave studio for design of antenna and tubes. For one design, several simulations have done to get the optimized results for physical fabrications. There are many advantages associated with simulation software to save time and money both. But it is necessary to have a proper and full understanding of any software otherwise several problems in analysis can be faced.

Thanks,

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

/POST1

SET,LAST

*GET,ST,ACTIVE,0,SET,LSTP ! ST steps

*GET,SS,ACTIVE,0,SET,SBST ! SS substeps

*DO,J,1,ST

/POST1

SET,J

PLNSOL, TEMP,, 0

/REPLOT

ESEL,S,LIVE

*ENDDO

*GET,NTEMP_12550,NODE,12550,BFE,TEMP

It worked for me.

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

Muhamad Alim Can you share your Ansys model in .cdb format?

Sir did you find the answer of this because on the same problem I am working on it.

Actually, it depends on the kind of mesh you want to create: unstructured or structured. Because of the simplicity of the geometry I recommend the structured type. At the beginning, suppose that there are just one zone and create an O-Grid type for the whole geometry and do all the association processes. In the end, just split the block in the separation point and then associate the faces of blocks to the surfaces of the geometry. Note that you have just one surface between the two zones you can name it interior. Because of all mesh elements are coincident you can give it the interior boundary condition and so the precision of your simulation will be higher than the interface boundary type. You can see some useful tutorial videos in my youtube channel "infinitycfd" with this link:

In simulations using finite element analysis (FEA) software, such as ABAQUS, it is generally possible to customize field outputs for individual materials in a bimaterial specimen tension test simulation. This allows you to extract and visualize specific results or quantities of interest for each material in the model.

Easiest way to create local cs is to use workplane, which is not just a plane, but also a work cs.

In the rolling simulation, you might also just pin the wheel axis and simply move the rail, in which case you would not need any local cs.

Abhishek Chawan

You can check for the mass vs time plot. consider the initial and final mass to get to know about the eroded mass during the 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.

Sir @Tomáš Létal, I also tested the contact statut using the CNCHECK,Auto command and it gives these results about contact statut analysis. Maybe this can give more complet information about the contact definition.

Discrepancies between the specified step time and the actual step time in ANSYS simulations may be due to many reasons. An important factor is the use of adaptive time stepping, in which the solver automatically modifies time intervals according to the changing dynamics of the system. This adaptive methodology enables the use of smaller increments in regions characterized by quick variations or significant occurrences, while using bigger increments in more stable areas, hence enhancing computing efficiency and solution precision. Furthermore, changes in step time are influenced by convergence criteria, solver settings, automated time stepping modifications, the selection of time integration methods, and the intricacy of boundary conditions and material models. To better match the user-defined step time with the simulation's actual steps, it is advisable to analyze the solver output, convergence logs, and maybe make tweaks to the solver parameters.

Dear sir @Ajibike Joan Farounbi really thank you so much for your important answer thank you. Definitely, when I got results it seems that in step 1 the program detect contact between wheel and the rail while in step 2 program don't detect any contact and the wheel continue traveling in vertical direction as there is no rail. Please sir @Ajibike Joan Farounbi if you can show me how can I apply your solution in Apdl?

I think you need transient analysis you can check the videos and search about on this way

Dear @Ajibike Joan Farounbi really many thanks for considering my question. I just wanted to mention that I used Cerig, Apdl command to couple the wheel nodes to the pilot node at its center refered as (numbernodes+1) in the code. Is this is equivalent to CP command?

Thank you so much for answering my question.

Sincerely yours

Kindly understand that the other well known name of Lamb wave is "Plate wave". This means that two Rayleigh waves are generated at the two sides of the plate simultaneously and they they travel without any interference first. Accordingly, plate thickness is being taken care of first to generate symmetrical mode Lamb waves. Then if the plate thickness is getting reduced then one can produce asymmetrical Lamb waves. Rayleigh wave wavelength, its frequency, plate thickness, material attenuation, etc. are the important considerations...

Kindly refer Symmetric and Asymmetric Lamb waves in the Google search...

Hi...

Refer this video. May be helpful..

1. You have to decrease the load increment size to simulate the process quasi-statically. So, at first, reduce the load increment size.

2. Then check that the kinetic energy evolution must be less than 1/10 to 1/20 of the strain energy. Otherwise, dynamics in the system exist.

3. If the problem persists, check the boundary condition and try it with elastic material.

For to deal void fraction you can check my tutorial on https://youtu.be/wybm2DavpRc

Bubble Flow due to Buoyancy Flow

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

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

Hajar Rhylane

1. Identify the remote location: Determine the remote location where you want to apply the load. This location can be specified using a node, element, or coordinate system.

2. Define the remote load: Use the *CLOAD command to define the remote load. Specify the appropriate options and parameters based on your specific load requirements. Here's the general syntax of the *CLOAD command:

````apdl

*CLOAD, Lab, Lab, Value

```

- `Lab`: Specify the label of the remote location where the load is applied. This can be a node label, element label, or coordinate system label.

- `Value`: Specify the load value or expression to be applied at the remote location.

Note that the `Lab` argument can be a single label or a range of labels, depending on the type of remote location you are using.

3. Repeat as needed: If you have multiple remote locations or different load values to apply, repeat step 2 for each remote load.

4. Generate the load: Finally, issue the *SOLVE command to generate the remote loads and solve the analysis.

Hajar Rhylane Tomáš Létal

1. Identify the node and surface nodes: Determine the node number and the surface nodes to which you want to create the rigid link.

2. Define the node set: Create a node set that includes the node you want to link. You can use the *NSEL command to select the node(s) and assign them to a set. For example:

````

*NSEL, N, , , node_number

*NSUBSET, node_set_name

```

Replace `node_number` with the actual node number and `node_set_name` with a suitable name for the node set.

3. Define the surface set: Create a surface set that includes the surface nodes you want to link to. You can use the *ASEL command to select the surface nodes and assign them to a set. For example:

````

*ASEL, S, , , , , , , , surface_nodes

*SSUBSET, surface_set_name

```

Replace `surface_nodes` with the appropriate selection criteria for the surface nodes and `surface_set_name` with a suitable name for the surface set.

4. Define the rigid link: Use the *CONSTRAINT command to define the rigid link between the node and the surface nodes. Specify the node set and surface set names created in the previous steps. For example:

````

*CONSTRAINT, TYPE=RIGID, NODE=node_set_name, SURFACE=surface_set_name

```

Replace `node_set_name` and `surface_set_name` with the names you assigned to the node set and surface set, respectively.

5. Repeat as needed: If you have multiple nodes or surface sets to link, repeat steps 2 to 4 for each node and surface set combination.

6. Generate the rigid link: Finally, issue the *SOLVE command to generate the rigid links and solve the analysis.

Good luck: credit partial AI

Joshua Depiver Hello , can you please help me with this concern ?

i use USDFLD to compute phase fractions (3 phases) , law kinetics are written in SDVs , everything seems working good except the fact that i have negative values in the middle of my axsymmetric model , negative values are displayed also in the legend of SDVs which is not reasonable at all ?

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

Double check your blade design please.

Just use Mechanical APDL and view .rst file in Results Viewer

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.

Kouider Bendine I found a couple of problems in the code.

First, the contact surfaces are defined as areas, but using elements CONTA175 (node-to-surface). I tried with CONTA174 (surface-to-surface) and it reaches the last substep. Here's how I defined the contact element:

ET,3,CONTA174

KEYOPT,3,2,1 ! Formulation: MPC

KEYOPT,3,4,1 ! MPC - Force-distributed constraint

KEYOPT,3,12,5 ! Bonded (always)

Then, the top cylinder was not properly contrained. I tried constraining the model like if modelling only a quarter of the system - double symmetry. For a quick test without changing the actual model I just did this:

ALLSEL

NSEL,S,LOC,Z,0

D,ALL,UZ,0

ALLSEL

ESEL,S,TYPE,,2

NSLE,S,1

NSEL,R,LOC,X,Lb/2

D,ALL,UX,0

Now the model converges and I can access the stress results in all substeps. Probably still have to adjust the contact surfaces to avoid stress concentration.

It's hard to say what's the problem without more details. However, the three key parameters controlling the structure self-weight are geometry, material density, and gravity acceleration.

Assuming a 10-mm-thick steel shell and a Y vertical axis, here's what you'd have to define in your Ansys APDL code:

SECTYPE,1,SHELL

SECDATA,0.010 !(m), thickness

MP, DENS, 1, 7850 !(kg/m3), density

ACEL, 0, 9.81, 0 !(m/s2), gravity

It often occur in non uniform body meshing. you Just try meshing all body creatures independently instead of once. just right click on creature and mesh.

Also, try the the right meshing pattern for right place specially on edges, holes etc..

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

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.

In that case, I would recommend you do all the analyses in the Mechanical APDL. Using APDL scripting in Workbench is possible, but not very user friendly. You basically need to be very proficient in it. On the other hand, in the old Mechanical APDL environment, all the actions you take using GUI are automatically recorded in a macro file, which you can then edit and run again. You can learn quite a lot this way.

Mohamed A M Salem Here you go. All you need is the free education edition of PERMAS. See https://www.intes.de/k_permas/overview/academic_license

Dear Shubham Patil,

Have you ever considered using SpaceClaim instead of DesignModeler?

In SpaceClaim, you could create a section with all the particles and remove them from the matrix. Then, before moving to the meshing step, you will need to activate the "Share topology" option so that the features will have a conformal mesh.

Then, I would recommend you to generate your geometry with a Python script inside SpaceClaim too, so that you can parameterize the problem easily.

I hope it helps.

Cheers,

Ramiro

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?

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.

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.

Did you find the answer? Thank you

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.

The optimal concentration of nanoparticles in nanofluids for battery cooling depends on the trade-off between the enhanced heat transfer and the increased pumping power required to circulate the nanofluid. Generally, higher concentrations of nanoparticles result in higher heat transfer coefficients, but also higher pressure drops and pumping power. Therefore, it is important to choose a suitable concentration that can achieve a balance between these factors. Concentrations ranging from 0.5% to 5% volume fraction can provide significant improvements in heat transfer without excessive penalties in pumping power for battery cooling applications