residual and initial state of thruster nozzle

side_al · October 4, 2009, 08:28

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:

using the 1st order convection in the turbulence flow menu
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.

October 4, 2009, 08:28	residual and initial state of thruster nozzle	#1
side_al New Member Syed Daniel Shukri Join Date: Jul 2009 Posts: 2 Rep Power: 0	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

October 7, 2009, 03:38		#3
side_al New Member Syed Daniel Shukri Join Date: Jul 2009 Posts: 2 Rep Power: 0	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: using the 1st order convection in the turbulence flow menu 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

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October 6, 2009, 17:16		#2
vishyaroon Senior Member Aroon Join Date: Apr 2009 Location: Racine WI Posts: 148 Rep Power: 17	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.

October 7, 2009, 15:47		#4
vishyaroon Senior Member Aroon Join Date: Apr 2009 Location: Racine WI Posts: 148 Rep Power: 17	Is the Cell quality remediation switched on in your Physics model? This often helps in solving divergence problems related to turbulence equations.

October 9, 2009, 05:02		#5
Maddin Senior Member Join Date: Mar 2009 Posts: 260 Rep Power: 18	Turn the normalization option of the residuals off.