What exactly mean by free stream condition? and what is the criteria for choosing it.

if I am calculting flow in a channel for internal flow case and flow past circular cylinder for external flow case . then what should be my free stream velocities and pressure.

My flow equation is 2d Navier stokes.

Thanks

The inflow primitive values like M_in, P_in, T_in...are considered as free stream conditions to accelerate the convergence. Since the flow is affected in a small part of the domain(Otherpart remains freestream), this initial condition will work far better than zero initial condition.

Freestream condns are one of the best initial conditions to start the simulation. Since its a uniform value, finally you will get zero diffusion and zero acceleration. so LHS and RHS part of the N-S eqns become zero.

For channel flow and cylinder case, use inflow conditions as a freestream condn,,,,

Bye Mohamed