Hi,
I need to perform FSI simulations on a lid-driven cavity (here an example of the configuration). I use CalculiX to compute the structure part of the problem, preCICE for the coupling and an in-house code for the CFD part.
To model the lid, I wish to use a *MEMBRANE SECTION. The initial mesh is generated using the following script using cgx:
# Define side length
valu c 1.0
# Define points and line to generate the geometry
pnt p1 0.0 0.0 0.0
pnt p2 0.0 0.0 c
line l1 p1 p2 1
swep all new tra c 0 0
# Group all sides together
seta sides l l1 L001 L002 L003
# Generate the mesh
div sides 32
elty all qu4
mesh all
# Group all nodes together
seta nodes n all
# Group nodes by boundary conditions
enq nodes right rec c _ _ 0.0001
enq nodes bottom rec _ _ c 0.0001
enq nodes left rec 0.0 _ _ 0.0001
enq nodes top rec _ _ 0.0 0.0001
enq nodes fsiinterface rec _ 0.0 _ 0.0001
# Write all nodes to their respective files
send all abq
send right abq nam
send left abq nam
send top abq nam
send bottom abq nam
send fsiinterface abq nam
# Inspection with cgx
view elem
plot f all
The mesh is fed to ccx using another script and I define the element type here:
********************************************************
** MATERIAL MODEL
********************************************************
*MATERIAL,NAME=LID
*ELASTIC, TYPE=ISO
250.0,0.3
*DENSITY
500.0
*ELEMENT, TYPE=M3D4, ELSET=Eall
*MEMBRANE SECTION, ELSET=Eall, MATERIAL=LID
0.0002
This code creates the following error:
*ERROR reading *MEMBRANE SECTION: *MEMBRANE SECTION can
only be used for membrane elements.
Element 1 is not a membrane element.
*INFO reading *STEP: nonlinear geometric
effects are turned on
*ERROR in gen3delem: first thickness
in node 1 of element 1
is zero
When checking the .msh file, the element type chosen by cgx is TYPE=S4. When replacing, the S4 type with M3D4, I don’t get any errors. The mesh generation script works fine if I use *SHELL SECTION as S4 elements are used for shells.
I can’t find any information on how to generate membrane elements from cgx in the documentation. What is the usual procedure to define a membrane properly?
Feel free to ask for additional information if you need it. I will continue to search for a solution.
Thank you in advance for your help.