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Convergence

Posted January 16, 2013 at 15:45 by arashsk

Quote:
Originally Posted by Centurion2011 View Post
I see all kind of mistakes on these forums when dealing with convergence, so I will give brief review of methods...

At convergence, the following should be satisfied:
  • All discrete conservation equations (momentum, energy, etc.) are obeyed in all cells to a specified tolerance OR the solution no longer changes with subsequent iterations.
  • Overall mass, momentum, energy, and scalar balances are achieved.
  • Monitoring convergence using residual history:
  • Generally, a decrease
...
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Old

Transient Temperature Profile

Posted January 16, 2013 at 10:04 by diamondx

UDF for a transient temperature profile


Quote:
Originally Posted by alven299 View Post
Have figured it out. Here is the script, hope it might be of help to others:

#include "udf.h"

DEFINE_PROFILE(inlet_temperature,t,i)
{
real x[ND_ND];
real time;
face_t f;

begin_f_loop(f,t)
{
F_CENTROID(x,f,t);
time=CURRENT_TIME;
if(time<40)
F_PROFILE(f,t,i)=300;

else

F_PROFILE(f,t,i)=340;
...
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Exporting blocking/mesh for a similar geometry By simon

Posted January 6, 2013 at 19:23 by diamondx

During import, you can also associate the new geometry file with the old tetin file so all the family sizes, etc. are preserved... This is an option near the top of the import DEZ.

Then load the old blocking file and update the associations.

If they don't all auto associate properly, you can use the interactive controls to adjust things...
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scale factor By simon

Posted January 6, 2013 at 19:17 by diamondx

Scale factor lets you adjust all the sizes in the model at once...

By default, you should probably leave it as 1, which means that all the other sizes could be taken at face value.

Then if you want to make the model 20% coarser, you can come back and set the scale factor as 1.2. Get it?

Scale Factor times Max Element size gives you the largest element in your model. For Octree, this is the size of the initial subdivision when Octree is first initialized....
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Hexadominant method...

Posted December 20, 2012 at 11:42 by diamondx

I agree with "Far", but don't recommend the Hexadominant method for CFD.

The Hexadominant method starts by paving quads at the walls and then marches inward with isotropic hexas which can crash somewhat badly in the middle. This is good for FEA structural analysis where most of the interesting stuff happens near the surface and uniform elements are sufficient to capture it all, but it is not good for CFD.

However, if you tried Multizone (or sweep) with...
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