[Nek5000-users] Stream function

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

Hi,
To correctly compute the stream function, the rhs of the Poisson 
equation needs to be the (negative) vorticity. Therefore, the line

    call col2(rhs,bm1,n)

is wrong, and should be something like

    call col3(rhs, vorticity, bm1, n)

where vorticity should be the computed vorticity using comp_vort.

I guess your calculation of delta* only works for parallel boundary layers.

Philipp



On 2018-06-26 18:35, nek5000-users at lists.mcs.anl.gov wrote:
> Hi Phillip,
> 
> I am using the “Blasius” example test outputting the streamfunction as a 
> scalar.
> 
> I included my code below. I am not sure what I am doing wrong.
> 
> In userchk, I added “compute streamfunction from vorticity” from the 
> psi_omega example, but it does not compute the psi properly… (max_psi = 
> min_psi = 0 in every step)
> 
> c-----------------------------------------------------------------------
> 
>        subroutine userchk
> 
>        include 'SIZE'
> 
>        include 'TOTAL'
> 
>        common /myblas/ ub(lx1,ly1,lz1,lelt),vb(lx1,ly1,lz1,lelt)
> 
>        common /blasiusr/ u(lx1,ly1,lz1,lelv),v(lx1,ly1,lz1,lelv)
> 
>        common /blasiusg/ bin(lx1,ly1,lz1,lelv)
> 
>        common /scrns/    dum(lx1*ly1*lz1*lelv)
> 
>        common /xtream/ psi(lx1*ly1*lz1*lelt)
> 
>       $              , rhs(lx1*ly1*lz1*lelt)
> 
>       $              , h1 (lx1*ly1*lz1*lelt)
> 
>       $              , h2 (lx1*ly1*lz1*lelt)
> 
>        integer bin
> 
>        real normu(50),normv(50)
> 
>        real xmax,xmin,dx
> 
>        save xmax,xmin,dx
> 
>        n = nx1*ny1*nz1*nelv
> 
> c. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
> 
> c     Compute streamfunction from vorticity
> 
>        call col2(rhs,bm1,n)
> 
>        call rone (h1 ,n)
> 
>        call rzero(h2 ,n)
> 
>        tol = param(22)
> 
>        imsh   = 1
> 
>        call hmholtz('psi ',psi,rhs,h1,h2,v1mask,vmult,imsh,tol,200,1)
> 
> c. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
> 
>        if (istep.eq.0) call outpost(vx,vy,vz,pr,psi,'   ')
> 
> c     Compute delta*
> 
>        do i=1,n
> 
>           dum(i) = 1.-vx(i,1,1,1)
> 
>        enddo
> 
>        tot_deficit = glsc2(dum,bm1,n)
> 
>        xmin        = glmin(xm1,n)
> 
>        xmax        = glmax(xm1,n)
> 
>        delta_star  = tot_deficit/(xmax-xmin)
> 
>        psimin      = glmin(psi,n)
> 
>        psimax      = glmax(psi,n)
> 
>        if (nid.eq.0) write(6,1) istep,time,delta_star,psimin,psimax
> 
>      1 format(i8,1p4e13.5,'  blasius: delta*')
> 
>        return
> 
>        end
> 
> 
> 
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