turbulance parameter
 

Hi

1- what is the mean of pressure in flow 3d? dynamic or static?
2- what is the mean of turbulent energy? is the same kinetic energy of turbulence?
k=0.5(u'2+v'2+w'2)
u', v', w' are Average volatility.

thanks a lot .

1) p = static pressure.
2) turbulent energy = turbulent kinetic energy, TKE, just as you have guessed:

k = 0.5(u'^2+v'^2+w'^2). TKE has units of L^2/t^2 (J/kg in SI).

On the Simulation Manager tab (and in Analyze > Probe > General History Data) there is an output called "mass-averaged turbulent energy":

MTKE = sum(k*mass)/sum(mass). In FLOW-3D variables,

MTKE = sum(k*rho*f*vf*del)/sum(rho*f*vf*del).

Rho is local fluid density, f is local fluid fraction (volume fluid in cell/open volume in cell), and vf is local volume fraction (open volume in cell/total volume in cell), and del is the cell volume dx*dy*dz. The term rho*f*vf*del = mass of fluid in cell.

turbulent dissipation
 

hello, thank you for your answers:
please tell me, what is the differences between turbulent energy and turbulent dissipation?
turbulent dissipation is reynolds stresses?if not, what's its formula?
i need u' , v' , w' , can i have these from out put result?

hi razieh
(i need u' , v' , w' , can i have these from out put result?)
can you solve this problem?

You can get u', v', w' from LES turbulence modeling. You can't get the velocity fluctuation components separately from RANS turbulence (like k-e or k-w).

Hi JBurnham
thank u
but, How do i get u', v', w' from output??

Use FlowSight (the new post-processor that comes with v11). It can calculate the time-mean velocity values u_, v_, w_ in all cells over a steady-state flow. Then have FlowSight perform an arithmetic operation to subtract: u, v, w - u_, v_, w_ = u', v', w'. From the new fluctuation variables, you can find the max/min, 95th percentile, etc.