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-   -   how calculate the density in low mach number? (https://www.cfd-online.com/Forums/main/1099-how-calculate-density-low-mach-number.html)

 Juhee Lee July 28, 1999 16:22

how calculate the density in low mach number?

hi, i am working on euler eq in low mach number with preconditioning. in actual, the euler code is compressible code, so its unknown is density, velociy, tempreture. the computation code is like this.

dWv dE dF

T ---- + ---- + ---- = 0

dt dx dy

where Wv=(p,u,v,t)

E =(rho u, rho u u + p , rho u v, rho u e + u p)

F =(rho u, rho u v , rho v v + p, rho u e + u p)

T - arbitrary preconditioning matrix p - pressure rho - density u,v - velocity component e - total energy

* all veriables are non-dimensionilized.

for clatulating the flux term(E,F), we should know density but the density is not present explicitly.

as i know p/rho = gamma R T (prefect gas eq) is not avaible owing to imcompressible and non-dimension. i shouble use artificial mach number or something else but i don't know.