[Nek5000-users] Compute the derivatives
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Thu Jul 1 19:57:07 CDT 2010
Hi Paul and Aleks,
I have a question regarding this. I have implemented this and it is working nicely, however it is dumping
out a .f file every step, rather than every iotime step I have specified in the rea.
Do you know how to fix this?
- Michael
----- Original Message -----
From: nek5000-users at lists.mcs.anl.gov
To: nek5000-users at lists.mcs.anl.gov
Sent: Wednesday, June 2, 2010 10:57:41 AM GMT -06:00 US/Canada Central
Subject: Re: [Nek5000-users] Compute the derivatives
Hi JC,
To dump the computed derivatives into separate field files you can use in
userchk
ifxyo = .true. ! for cooordinates
ifpo = .false. ! turn off pressure output
ifto = .false. ! turn off pressure output
call outpost(vxx,vxy,vxz,pr,t,'dvx')
call outpost(vyx,vyy,vyz,pr,t,'dvy')
...
Best,
Aleks
On Wed, 2 Jun 2010, nek5000-users at lists.mcs.anl.gov wrote:
>
> dudxyz is somewhat dated and slow...
>
> I recommend somthing like:
>
> parameter (lt=lx1*ly1*lz1*lelv)
> common /mygrad/ vxx(lt),vxy(lt),vxz(lt)
> $ , vyx(lt),vyy(lt),vyz(lt)
> $ , vzx(lt),vzy(lt),vzz(lt)
>
> call gradm1(vxx,vxy,vxz,vx)
> call gradm1(vyx,vyy,vyz,vy)
> call gradm1(vzx,vzy,vzz,vz)
>
> Note that putting these arrays into a common block, as
> shown, is a good idea for several reasons, one of which
> is that it guarantees that the data will be byte-aligned with the cache line.
> On some machines (e.g., BG/P) this
> is crucial for proper functionality - for this reason we
> don't mix variable types in a given common block.
>
> If you subsequently wish to access elements of vxx etc.
> on an element-by-element basis you can of course do something
> like
>
> parameter (lt=lx1*ly1*lz1)
> common /mygrad/ vxx(lt,lelt),vxy(lt,lelt),vxz(lt,lelt)
> :
> :
>
> Paul
>
> On Wed, 2 Jun 2010, nek5000-users at lists.mcs.anl.gov wrote:
>
>> Hi Nek's,
>>
>> I have a home-made global stability code, but in order to use it I first
>> need to compute the derivatives of my base flow: dUdX, dUdY, dVdX, dVdY.
>> How could one compute these derivatives using Nek 5k and drop them along
>> with X Y U V in the blah.f**** file (or perhaps another .f**** file) ? I
>> assume I have to make use of the subroutine *dudxyz
>> (du,u,rm1,sm1,tm1,jm1,imsh,isd)*, but I'm not sure what to put as inputs.
>>
>> Regards,
>> JC
>>
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