K-Epsilon Model

[lweb]

Dear Elmer users,

does anybody know what the parameter "KE Clip" in the K-Epsilon model means?
Path in ElmerGUI: Model --> Material --> K-Epsilon: Properties: KE Clip

Many thanks in advance,
lweb

[cemg]

Hi Iweb,

the KE Clip is a limiter. The turbulent kinetic energy and its dissipation must be positive, so, to ensure it, the following condition is applied to all the nodal values of the variables (KESolver.src, lines 428 to 451):

Code: Select all

!------------------------------------------------------------------------------
!      Kinetic Energy Solution should be positive
!------------------------------------------------------------------------------
      n = Solver % Mesh % NumberOfNodes
      Kmax = MAXVAL( Solver % Variable % Values(1:n:2) )
      Emax = MAXVAL( Solver % Variable % Values(2:n:2) )
      DO i=1,n
         k = Solver % Variable % Perm(i)
         IF ( k <= 0 ) CYCLE

         Kval = Solver % Variable % Values(2*k-1)
         Eval = Solver % Variable % Values(2*k-0)

         IF ( KVal < Clip*Kmax ) Kval = Clip*KMax

         IF ( Eval < Clip*EMax ) THEN
            KVal = Clip*EMax
            Eval = MAX(Density(1)*KECmu(1)*KVal**2/Viscosity(1),Clip*EMax)
         END IF

         Solver % Variable % Values(2*k-1) = MAX( KVal, 1.0d-10 )
         Solver % Variable % Values(2*k-0) = MAX( EVal, 1.0d-10 )
      END DO
!------------------------------------------------------------------------------

Regards,

Cesar