I am working in the field of supersonic fluid dynamics. The main topics contain: 1. the supersonic nozzle design 2. supersonic flows simulation (The important parameters are pressure, velocity, density and so on.) 3. supersonic nozzle optimization

Can anybody give me the idea about which code can work well with these topics?

StarCCM+

Try Gasp from Aerosft. Note no O in soft! Came out of NASA/Vulcan heritage.

Question for A.S - what mach number have you pushed Star-CCC to? My experience with star predates CCM and going much past transonic in V3.X was not too easy.

Currently using GASP and FLUENT. We push FLUENT upto about mach 3-4 . GASP we can go as high as 20, but it isn't alll that robust with subsonic flows.

My2cents - Andy

Mach 20 Nozzle

Compressible flow -> use CFX with coupled solver. Will give you an answer in no time. But for for flows beyond Mach 3-4 I would not use the major commercial codes. Use density based codes instead with proper shock handling. You might want to write your own Euler solver (with boundary layer displacement thickness correction). It's fast, cheap and may help you to design your particular nozzle fast. Do this only for relatively simple geometries.

Bart

Hello, Your site is great. Regards, Valintino Guxxi

Which site? CFD-online?

AS, Did your Mach20 Nozzle include any chemistry? Temperature dependent properties? What total temp/pressure did you have upstream of the nozzle? Is this a solution you could share?

We would be very interested to see a high end commercial code (as opposed to a NASA derivitive product) that can operate in that flow regime.

Thanks - Andy R

Question: How to choose a time step? Answer: An optimal time step depends on the used mathematical model. General recommendations are as follows:

Solid Material: take the time step as one tenth of the body heating time: , where l is the characteristic size of the body, is the coefficient of thermal diffusivity.

Laminar Fluid, k-e turbulence model, Weak Compressible Fluid, Combustion Model: take the time step as one tenth of the ratio of the characteristic length of the domain in the steramwise direction to the characteristic flow speed.

Free Surface: the time step is determined by the condition that the Courant number equals 1.

Full compressible: the time step must provide fast convergence of the pressure calculations. The initial step is specified similarly to Laminar Fluid, k-e turbulence model etc. If the pressure calculations diverge, decrease the time step. If conjugate heat transfer is concerned and a steady solution is sought, different time steps can be defined in the fluid and solid body in order to accelerate convergence to the solution. Select the Use Own Time Step and Step check boxes on the Enthalpy tab in the Method parameters window of the solid sub-region. Enter the CFL number or the global time step in the Step dialog box. Normally, the time step in solid body is higher than that in fluid.

Can anybody send code for supersonic nozzle design using moc for M 3.5?