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Defining Boundry Conditions


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#1 Mr. Salman Bin Kashif

Mr. Salman Bin Kashif

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Posted 22 June 2015 - 04:33 PM

I have a T shaped cylindrical geometry. I want to define an inlet from two ends giving inlet velocity to two different fluids and give a pressure condition at the outlet. Mesh it and solve to obtain pressure and velocity contours in the end.

 

There is a tutorial on post processing but could not find to define the inlet and outlet surfaces and the conditions.

 

Can anyone suggest the way out?

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#2 Matthias Maasch

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Posted 22 June 2015 - 07:47 PM

Dear Salman,

 

CAESES is capable of geometry preprocessing which includes e.g. to convert an surface model (IGES) into an surface-meshed model (STL -- represented by trimeshes or solids within the software) and CAE results postprocessing, but it does not include an CFD code, no volume mesher and no CFD-preprocessing such as applying boundary condtions. These steps have to be done in a another software (OpenFOAM + Snappy Hex Mesh, STAR-CCM+, ...). 

 

If you have a surface geometry available (although your screenshot above looks like a single object -- already a STL geometry I guess) you can mesh the surface in CAESES. For the meshing you can apply e.g. different colors to the inlet patches and the outlet patch. Then you can export your geometry as colored STL which will help you to easily apply different boundary conditions to the different patches.

 

The general approach is to set up a software connector in CAESES, pass your surface mesh geometry to the external mesher and CFD code and receive the results after the CFD run. Then you can postprocess them using CAESES again. If you have a parametric geometry or if you want to run different cases (e.g. flow speeds, pressures, ...) you can use CAESES to compare and analyse all the results in an easy and smart way. The tutorials "Basic Preprocessing" and "External Software" will teach you this procedure.

 

I hope this helps a bit. If you have further questions do not hesitate to ask. Furthermore I would be happy if you could share some more information. Which CFD code you want to use/ you have available? Can you share your geometry? ...

 

Best regards

 

Matthias


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#3 Mr. Salman Bin Kashif

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Posted 23 June 2015 - 03:11 AM

Dear Mr. Maasch,

 

Thank you for your kind response.

 

I wanted to define this geometry as fluid domain with the two openings as inlet and the other opening as outlet and I have built this geometry by combining 3 cylinders.

 

The way further is:

 

Converting this to fluid domain and defining the two liquids whose pressure contours contours I need to examine. However, going by what you said, this will require external solver.

 

The other thing of changing the colors of inlet and outlet require the surface to be selected. However, the selection tool by default is volume tool. I tried selecting the surface using the filter tool but was unable to do. Could you suggest the relevant way to select the three openings as surfaces.

 

I intend to use the Ansys CFX solver.

 

Thank you

 

Regards,

 

Salman

Dear Salman,

 

CAESES is capable of geometry preprocessing which includes e.g. to convert an surface model (IGES) into an surface-meshed model (STL -- represented by trimeshes or solids within the software) and CAE results postprocessing, but it does not include an CFD code, no volume mesher and no CFD-preprocessing such as applying boundary condtions. These steps have to be done in a another software (OpenFOAM + Snappy Hex Mesh, STAR-CCM+, ...). 

 

If you have a surface geometry available (although your screenshot above looks like a single object -- already a STL geometry I guess) you can mesh the surface in CAESES. For the meshing you can apply e.g. different colors to the inlet patches and the outlet patch. Then you can export your geometry as colored STL which will help you to easily apply different boundary conditions to the different patches.

 

The general approach is to set up a software connector in CAESES, pass your surface mesh geometry to the external mesher and CFD code and receive the results after the CFD run. Then you can postprocess them using CAESES again. If you have a parametric geometry or if you want to run different cases (e.g. flow speeds, pressures, ...) you can use CAESES to compare and analyse all the results in an easy and smart way. The tutorials "Basic Preprocessing" and "External Software" will teach you this procedure.

 

I hope this helps a bit. If you have further questions do not hesitate to ask. Furthermore I would be happy if you could share some more information. Which CFD code you want to use/ you have available? Can you share your geometry? ...

 

Best regards

 

Matthias


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#4 Mr. Carsten Fuetterer

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Posted 23 June 2015 - 09:39 AM

Hi,

 

I recorded a short video to show how boundaries of a trimesh can be colored. When you export this trimesh as multibody STL, each colored surface is written as an own patch in the stl.

 

I hope this helps you.

 

Carsten

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Carsten Fütterer
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#5 Matthias Maasch

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Posted 24 June 2015 - 09:18 AM

Dear Salman,

 

if you have solved your issues already, you can ignore this post.

 

If not -- to be honest, I am still not sure what kind of model you have. Can you share it either here in the Forum or send it to me via email?

 

Anyway, I set up a simple copy of what I can see in the screenshot above. Two pipes intersecting each other, coloured inlet and outlet, parametrized. In the project you will find a couple of parameters controlling the dimensions, each radius, each lenght and the angle of the second pipe with respect to the y-axis.

 

You can export the object "final" as coloured STL either to a software connector or to your hard disk.

 

I hope this helps.

 

Cheers

 

Matthias

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Matthias Maasch
Service and Support
www.caeses.com
TEL. +49 (0)331 967 66 0
maasch@friendship-systems.com