[Nek5000-users] Dissipation rate

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

Thank you Paul, your answer was really helpful


Le 2017-11-10 15:56, Samuel Ahizi a écrit :
> 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