CFD Online Logo CFD Online URL
Home > Forums > FLUENT

URGENT: External SS and HS Flow Modelling

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   August 12, 2002, 13:34
Default URGENT: External SS and HS Flow Modelling
Posts: n/a
Hi !

I am new to Fluent, I am using 5.5. To model Supersonic or Hypersonic External Aerodynamic flow while definig materials: How should I specify Density, Thermal Conductivity, Viscosity and Specific Heat? What should I do: specify them a constant? ideal gas law? polynomial, sutherland etc etc there are many options?

  Reply With Quote

Old   August 12, 2002, 15:58
Default Re: URGENT: External SS and HS Flow Modelling
Pierre-Antoine Rainville
Posts: n/a
For this problem, you probably work with air. It's certain that they have noumerous choice to fix it. For your first approximation, you chould fix your density with ideal gas law. It's a good and simple way to work in compressible flows. In this first guess, you can let Thermal conductivity and specific heat to default values. But, in futur operations, you should use polynomial fonctions for these parameters. For the viscosity, try default constant or Sutherland model with three constants.

For the kind of work you seem to do, you should work in the coupled code. The segregated code is mostly for incompressible calculations. To choose between implicit and explicit, a validation calculation could be interresting.

Good luck and patience
  Reply With Quote

Old   August 18, 2002, 10:51
Default Re: URGENT: External SS and HS Flow Modelling
Posts: n/a
Hi Mr. Antoine !

(a) I have tried the default values for Thermal Cond. and Specific Heat. I have also used Ideal Gas Law for Density and Sutherlands law with 3 Coeff. for viscosity. I have been able to get the results. But no matter what I do the residuals are not decreasing below 0.008.

I have monitored Cm, Cd and Cl also and they also get to one point and show no more change.

After that I have tried changing the under Relaxation factors as well, but the results are no more changing.

Have I got the converged results??

By seeing the soln, things appeared to be alright.

(b) Where can I find the polynomial functions for Specific Heat & Thermal Cond. in case of Air. I have tried but unable to find these properties of Air (Sp Heat & Therm. Cond.). Can you guide me wher to find these values w.r.t Temperature for Air. Definitely I need the values at high Tepmerature if I am modelling the flow at high Supersonic and Hypersonic regimes.

Thanx really for your previous help.

  Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 13:38.