Reynolds Number matching in Cavity flow
 

Hi, I was going through one of the test cases in cavity flows throuhg M219 cavity. ( www.qnet-cfd.net/workshop/3rd/pdf/ws3-03.pdf ). Test conditions are Mach number 0.85, Characteristic length 20 inches (length of cavity) and Reynolds number of 6.84e6. Temperature,density or pressure is not explicity stated. For this case we have the experimental windtunnel data available as well which I assume will have been on standard pressure and temperature conditions??. How to match the Reynolds number for given 20 in characteristic length and Mach no 0.85? As if I take STP (rho=1.225 kg/m3, velocity=295.11 m/s, length=20in=0.508m, meu=1.7894e-5, gives Re=10.263e6 which is greater than the test condition). I tried to vary the temperatures from 0-30 c but couldnot find any combination of rho,vel and meu to have the test reynolds no. Any suggestion is welcome. Endee

Re: Reynolds Number matching in Cavity flow
 

i think you must give how your RE is defined.

Re: Reynolds Number matching in Cavity flow
 

Reynolds number is based on the length of cavity and Mach nymber 0.85. No temperature, density or pressure is specified. But with in a realistic range of temperature 0-40 degree celcius, the corresponding velocity at Mach 0.85, characteristic length (20 in =.508 m) and molecular viscosity (meu) does not give that Reynolds number. It is rather more than that. Thanks

Re: Reynolds Number matching in Cavity flow
 

Hi,

As far I as remember, QinetiQ experimental data on M219 cavity flows include operating conditions such as stagnation pressure and temperature. For my computations on this case I was using a U_\infinity=276.45 m.s^-1 resulting in a Reynolds number of about 7 millions.

Best regards.

Re: Reynolds Number matching in Cavity flow
 

Hi,

Complementary to the previous message. The stagnation pressure and temperature I've used can be found somewhere in the following article : Larcheveque, Sagaut, Le and Comte, JFM 516, pp 265-301, 2004. Sorry, presently I have no copy of the article left to check the exact values. However I've managed to find a file containing the operating conditions for the experiments (in imperial units). If you're interested, just send me an email.

Regards,

Lionel

Re: Reynolds Number matching in Cavity flow
 

i am mechanical engineer. please send thise file for me. thanks.

lionel,i read your paper~Large-eddy simulation of a compressible flow in a three-dimensional open cavity at high Reynolds number~have you obtained any data about the heat on the wall of the cavity, thanks