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viscous layers in partition with netgen

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viscous layers in partition with netgen

Posted by Chaz at February 04. 2015


I am having difficulty making viscous layers in the gui or with scripts in a partition. I am using 7.4

I used netgen in the gui making a simple mesh with viscous layers on a simple cube, and it appears to work ok.

I have a partition with two regions, one solid, one fluid in the later analysis. I would like to create viscous layers on some of the surfaces of the fluid, in the fluid region.  Some of these faces are on the outside surface of the entire mesh, some are in the fluid, at the contact surface between the fluid and the solid region.

Is there a way to do this?  I looked up one the fourum, and found my post from 2012 with this problem, but also notes on how things have improved in 7.4.

When trying to select the faces for viscous layers in the gui, only one of the many layers is selectable (#4).  This layer is one of the exterior faces. 

I can dump the study, and use the syntax in a script to generate viscous layers.  When I try to add more than just surface 4, either the mesh generation crashes, or for some layer combinations, layer 4 gets a viscous layer, but other layers (0,1, and or 3, 4.... etc.) do not get any viscous layers.  Since I can't select  surfacs in the gui, I am just guessing at surface numbers, and hoping to see viscous layers form, and thereby find the right numbers to include in the script.

Also, if I could select layers in the script or the gui, how would I specify that the viscous layers be generated on the fluid side of the volume, for a surface at the fluid-solid interface? the layer as well as the normal to the layer would need to be specified, I would think.

Any ideas how I can make viscous layers?


Re: viscous layers in partition with netgen

Posted by Saint Michael at February 04. 2015

Hi Chaz

It's true that selection of faces for viscous layers in the Viewer of Mesh module is difficult or even impossible as faces hide one another. As a workaround one can create a group of faces in Geom module, providing more means for selection of hidden faces, and select the group in Mesh module.

To get viscous layers on a 'fluid side' of an internal face, you are to create a sub-mesh with Viscous Layers on a 'fluid solid'. Try the attached script.



Re: viscous layers in partition with netgen

Posted by Chaz at February 05. 2015

That screen shot looks very much like what I am trying to do.  I will take a look at the scipt,


Re: viscous layers in partition with netgen

Posted by Paul Dillon at November 29. 2021


I have a similar issue, when using a partition.  I want to avoid having boundary layers on some of the faces of the fluid region (corresonding to inlet and outlef flows). I can do this by defining groups for some of the fluid boundaries, and for the surface of the 'solid'.  However, at the solid surfaces, the vicous layers are generated on BOTH sides (inside and outside) of the surfaces. See picture below, and attached python dump.

is there a way to just get viscous layers on the outside of the solid i.e. in the 'fluid' region only ?

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