[Nek5000-users] Dissipation rate

[nek5000-users at lists.mcs.anl.gov]

Dear Nek experts,

I'm still working on the turbulent dissipation rate.
I would like to compute epsilon=2*nu*<Sij Sij> with 
Sij=0.5*(grad(U)+grad(U)^T)

I found in the forum a proposition to calculate the scalar dissipation 
rate as follow.

If I understood well, this code is basically doing "chi := D * |grad 
Z|^2" while I would like to compute chi := D * D * |grad Z + grad^T Z|^2

Does anyone have a suggestion ?

Many thanks,
Samuel

c-----------------------------------------------------------------------
        subroutine magSqr(a,b1,b2,b3,n)
        include 'SIZE'
        real a(1)
        real b1(1),b2(1),b3(1)

        do i=1,n
           a(i) = b1(i)*b1(i) + b2(i)*b2(i)
        enddo

        return
        end
c-----------------------------------------------------------------------
       subroutine scalDisp(chi,Z,D)
c
c    compute scalar dissipation rate
c    chi := D * |grad Z|^2
c
       include 'SIZE'
       include 'TOTAL'

       real chi(lx1,ly1,lz1,1)
       real Z  (lx1,ly1,lz1,1)
       real D  (lx1,ly1,lz1,1)

       common /scrns/ w1(lx1,ly1,lz1,lelt)
      $              ,w2(lx1,ly1,lz1,lelt)
      $              ,w3(lx1,ly1,lz1,lelt)

       ntot = nx1*ny1*nz1*nelv

       call opgrad (w1,w2,w3,Z)
       call opdssum(w1,w2,w3)
       call opcolv (w1,w2,w3,binvm1)

       call magsqr (chi,w1,w2,w3,ntot)
       call col2   (chi,D,ntot)

       return
       end
c-----------------------------------------------------------------------


Le 2017-11-08 10:55, Samuel Ahizi a écrit :
> Dear Neks,
> 
> I would like to compute the turbulent dissipation rate, in order to
> calculate the Kolmogorov microscales. Does a subroutine already exist
> or should I compute it from userchk ?
> 
> Thank you very much for your answers,
> Samuel