analyse of a hot cylinder over supersonic flow

hsm · February 22, 2012, 09:56

hi all
i want to analyse a cylinder over supersonic flow {thermal study and shock place) I model a symmetric 2D body in gambit and i apply these in fluent:
i used steady state density-based solution with spalart almaras for model of turbulency
i enabled the energy menu
i put the operating pressure zero
the boundary condition over the body was pressure far-field with mach Nom=2.5 and gauge pressure= 101235 pa and temp= 300 k
for the body i used wall condition with flux=0 (i didn't know how to apply the temperature of cylinder for example 450 k)
model for density was ideal gas and for viscosity i used Sutherland model
when i started the iteration after few second i got the floating point error and sth about the limitation of temperature and ...
where was the mistakes how can I get the answer in these problem
i really need the answer please help

hadikhayyamian · June 7, 2012, 14:27

Try lower Under-relaxation Factors. also u can start with disabling energy equation and then after some iteration you can enable it again.

are you sure that your mesh has enough quality, what is your maximum skewness?

Some times reasonable Initialization might help converging the model!

also for imposing fixed temperature, when Energy equation is enabled, if you go to "thermal" tab in your boundary condition, you can check "Tempearture" under "Thermal Condition".

February 22, 2012, 09:56	analyse of a hot cylinder over supersonic flow	#1
hsm New Member hessam Join Date: Feb 2012 Posts: 1 Rep Power: 0	hi all i want to analyse a cylinder over supersonic flow {thermal study and shock place) I model a symmetric 2D body in gambit and i apply these in fluent: i used steady state density-based solution with spalart almaras for model of turbulency i enabled the energy menu i put the operating pressure zero the boundary condition over the body was pressure far-field with mach Nom=2.5 and gauge pressure= 101235 pa and temp= 300 k for the body i used wall condition with flux=0 (i didn't know how to apply the temperature of cylinder for example 450 k) model for density was ideal gas and for viscosity i used Sutherland model when i started the iteration after few second i got the floating point error and sth about the limitation of temperature and ... where was the mistakes how can I get the answer in these problem i really need the answer please help

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June 7, 2012, 14:27		#2
hadikhayyamian Member Khayyamian Join Date: Dec 2010 Posts: 46 Rep Power: 15	Try lower Under-relaxation Factors. also u can start with disabling energy equation and then after some iteration you can enable it again. are you sure that your mesh has enough quality, what is your maximum skewness? Some times reasonable Initialization might help converging the model! also for imposing fixed temperature, when Energy equation is enabled, if you go to "thermal" tab in your boundary condition, you can check "Tempearture" under "Thermal Condition".