In Creating a Standard Mesh on a Heat Sink | Tutorial | SimScale at section “3. Standard Mesh” I read: “Automatic boundary layers generates layers automatically on all no-slip walls, based on the boundary conditions set by the user;”
So I thought I do not need an “Inflate boundary layer 2” in my Mesh (having “Automatic boundary layers” on) for the no-slip Boundary condition “Custom 4” (ground layer with no-slip Velocity type).
If I include this “Inflate boundary layer 2”, I see nicely three horizontal layers in the mesh, but If I remove it, these threee layers vanish (I while I still have “Automatic boundary layers” on in the Mesh.
So why do I still need to this “Inflate boundary layer 2”? What do I do wrong? Should I not do a "Custom’, but do a "Wall’ in the Boundary conditions?
Thanks.
Hi @jjansman,
The automatic boundary layers definition will be applied only to boundary conditions literally defined as “walls” with a no-slip characteristic, so the “Custom” one wouldn’t factor in.
As a sidenote, it’s good to stress that if no boundary condition is assigned to a wall, it will be automatically defined as a no-slip wall.
Cheers,
Igor
I did some further testing. I get the feel that both a “Wall Boundary Condition no-slip” and an “Inflate boundary layer 2” for the ground are essential.
If I leave away the “Wall Boundary Condition no-slip” (and thus also the “Inflate boundary layer 2”) the results are the same as only having the “Wall Boundary Condition”.
Adding “Inflate boundary layer 2” gives a different results.
I assume that the results of “Wall Boundary Condition no-slip” and an “Inflate boundary layer 2” are correct???
P.S. So I don’t understand the text In Creating a Standard Mesh on a Heat Sink | Tutorial | SimScale at section “3. Standard Mesh” I read: “Automatic boundary layers generates layers automatically on all no-slip walls, based on the boundary conditions set by the user;”
Hi @jjansman, could you add a project link so we can take a closer look at the tests you’re performing?
Here’s how to post a project link here: Guide to Clear and Understandable Forum Posting
Cheers
My project is here: Nageli henge measuremenets by jjansman | SimScale
No Wall and thus also the “Inflate boundary layer 2”
“Simulation”: 25m, 2.2m:5m/sec,ap=8.5, F=7.5, NoGround, CTB
“Simulation Run”: ap=0.085-Dir=010
Having only “Wall Boundary Condition: Wall4”. but No Inflate Boundary layer.
“Simulation”: 25m, 2.2m:5m/sec,ap=8.5, F=7.5, NoGround, CTB
“Simualtion Run”: ap=0.085-Dir=110-CTB-Ground-NoInfl
With ground (Custom 4) and Inflate Boundary layer:
“Simulation”: Kort, =17.5, z0=0.01m, Fineness=7.5
“Simulation run”: ap=8.5-010
In all above Mesh settings I always had “Automatic boundary layers” on (with same valuess as the Inflate Boundary layer.
<the Mesh settings are visisble in the “Simulation Runs”. So verifying may not be possible, as I experiment in this project with settings, not only the Simulation settings, but also the Mesh settings… But I think the Mesh settings in “Simulation” are still ok>
Does this help? Thanks for your help.
All the best,
I just realised that my last Simulation run:
With ground (Custom 4) and Inflate Boundary layer.
uses a different Boundary Condition! Custom instead of Wall. So I need to run another Simulation Run with using:
With ground (Wall 4) and Inflate Boundary layer.
That is now running:
Simulation: 25m, 2.2m:5m/sec,ap=8.5, F=7.5, NoGround,CTB
Simulation Run: ap=0.085-Dir=110-CTB-Ground-Infl
Well see what the output is there.
Sorry for this.
I now did the correct test!
So if I yes/no specify a “Boundary condition” Wall or yes/no default “Inflate Boundary layer”. all results are the same.
So the above documentatian statement and of yourself, is correct. I should indeed have seen the word Wall
Sorry I did the wrong test!!!
Thanks for your patience.
All the best.
No worries @jjansman! Thanks for sharing and glad that the issue is solved.
Cheers