CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   STAR-CCM+ (http://www.cfd-online.com/Forums/star-ccm/)
-   -   residual and initial state of thruster nozzle (http://www.cfd-online.com/Forums/star-ccm/68860-residual-initial-state-thruster-nozzle.html)

side_al October 4, 2009 08:28

residual and initial state of thruster nozzle
 
good day

my name is daniel.. i'm a final year bachelor student..

i had some trouble on my Final Year Project... i'm trying to observed the effect of altering the divergence angle and the divergence length on the CD nozzle..

i'm using Spallart Allmaras as my turbulence flow solver.. but its plot on my residual always diverge to the value of 10K.. sometime d iteration stop due to flowing point..

any pointer or paper is highly apritiated

S.D

vishyaroon October 6, 2009 17:16

Which of the equations causes the divergence? How is the mesh quality?

If it is the turbulence equation that starts the divergence, try activating the Cell Quality Remedaition.

side_al October 7, 2009 03:38

Spalart Allamaras is the solver..

in the residual.. the only diverge line is Sa_nut
my meshing quality is 0.1% of its original size

i'll try several method to avoid failure such as:
  1. using the 1st order convection in the turbulence flow menu
  2. and lowering the relaxation factor of the Spalart Allamaras
could this be done.. and is it valid..

ur point of viiew and comment is greatly appritiated

vishyaroon October 7, 2009 15:47

Is the Cell quality remediation switched on in your Physics model? This often helps in solving divergence problems related to turbulence equations.

Maddin October 9, 2009 05:02

Turn the normalization option of the residuals off.


All times are GMT -4. The time now is 18:43.