[Nek5000-users] Dissipation rate

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

Dear Samuel,


Several of these routines are in the turbchannel example .usr file (and nek5000 source).   Please have a look at the .usr file in that example and you'll see the below.


hth, Paul



      call comp_gije(sij,vx(1,1,1,e),vy(1,1,1,e),vz(1,1,1,e),e)

      call comp_sije(sij)


      call mag_tensor_e(snrm(1,e),sij)

      call cmult(snrm(1,e),2.0,ntot)



________________________________
From: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov> on behalf of nek5000-users at lists.mcs.anl.gov <nek5000-users at lists.mcs.anl.gov>
Sent: Friday, November 10, 2017 8:56:09 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: Re: [Nek5000-users] Dissipation rate

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
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