November 2011 - Nek5000-users - mailman3.cels.anl.gov

Re: [Nek5000-users] Vorticity
by nek5000-users＠lists.mcs.anl.gov 11 Oct '16

11 Oct '16

Hi, Thanks for your quick reply. Just I wanna know if I can use the interpolated values of velocity at some arbitrary points in the domain (not necessarily the grid points) as the input arguments to theses subroutines. Regards, Alireza Quoting nek5000-users-request(a)lists.mcs.anl.gov: > Send Nek5000-users mailing list submissions to > nek5000-users(a)lists.mcs.anl.gov > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users > or, via email, send a message with subject or body 'help' to > nek5000-users-request(a)lists.mcs.anl.gov > > You can reach the person managing the list at > nek5000-users-owner(a)lists.mcs.anl.gov > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Nek5000-users digest..." > > > Today's Topics: > > 1. Vorticity (nek5000-users(a)lists.mcs.anl.gov) > 2. Re: Vorticity (nek5000-users(a)lists.mcs.anl.gov) > 3. Re: Vorticity (nek5000-users(a)lists.mcs.anl.gov) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 13 Jul 2011 17:55:35 -0400 > From: nek5000-users(a)lists.mcs.anl.gov > Subject: [Nek5000-users] Vorticity > To: nek5000-users(a)lists.mcs.anl.gov > Message-ID: <20110713175535.1042430oct81vz2v(a)webmail.vt.edu> > Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes"; > format="flowed" > > Hi, > > I need to calculate the vorticity vector and the rate of strain tensor > at any arbitrary point in the domain. I wonder if these values are > computed somewhere in the code or if I should interpolate them in the > usr file. I appreciate any kind of help. > > Thanks in advance, > > > Regards, > Alireza Karimi > > > > ------------------------------ > > Message: 2 > Date: Wed, 13 Jul 2011 17:09:48 -0500 (CDT) > From: nek5000-users(a)lists.mcs.anl.gov > Subject: Re: [Nek5000-users] Vorticity > To: nek5000-users(a)lists.mcs.anl.gov > Message-ID: <Pine.LNX.4.64.1107131704140.26989(a)jacobi.mcs.anl.gov> > Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed > > Hi Alireza, > > For vorticity computation, you can call > > call comp_vort3(vort,work1,work2,vx,vy,vz) > > from userchk with the appropriate definitions of vorticity and work arrays > like > > common /scren/ vort (lx1,ly1,lz1,lelv,3) ! x y z components > $ , work1(lx1,ly1,lz1,lelv) > $ , work2(lx1,ly1,lz1,lelv) > > Let me check what we have for the calculation of strain tensor. > Best, > Aleks > > > On Wed, 13 Jul 2011, nek5000-users(a)lists.mcs.anl.gov wrote: > >> Hi, >> >> I need to calculate the vorticity vector and the rate of strain >> tensor at any >> arbitrary point in the domain. I wonder if these values are computed >> somewhere in the code or if I should interpolate them in the usr file. I >> appreciate any kind of help. >> >> Thanks in advance, >> >> >> Regards, >> Alireza Karimi >> >> _______________________________________________ >> Nek5000-users mailing list >> Nek5000-users(a)lists.mcs.anl.gov >> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users > > > ------------------------------ > > Message: 3 > Date: Wed, 13 Jul 2011 23:59:08 -0500 (CDT) > From: nek5000-users(a)lists.mcs.anl.gov > Subject: Re: [Nek5000-users] Vorticity > To: nek5000-users(a)lists.mcs.anl.gov > Message-ID: > <600285192.94128.1310619548370.JavaMail.root(a)zimbra.anl.gov> > Content-Type: text/plain; charset=utf-8 > > Hi Alireza, > > > For a strain stress computation you can call subroutine comp_sij > > call comp_sij(sij,nij,vx,vy,vz > $ ,ur,us,ut,vr,vs,vt,wr,ws,wt) > > > (navier5.f:2225) with nij=6 for 3D somewhere from userchk once you > declare the stress component array sij and arrays with local > coordinate r-s-t derivatives of velocity components > > common /csij/ > $ sij(lx1*ly1*lz1,6,lelv) ! 6 components > $ ,ur (lx1*ly1*lz1) > ... > $ ,wt (lx1*ly1*lz1) > > > Best, > Aleks > > > > > > > ----- Original Message ----- > From: nek5000-users(a)lists.mcs.anl.gov > To: nek5000-users(a)lists.mcs.anl.gov > Sent: Wednesday, July 13, 2011 5:09:48 PM > Subject: Re: [Nek5000-users] Vorticity > > Hi Alireza, > > For vorticity computation, you can call > > call comp_vort3(vort,work1,work2,vx,vy,vz) > > from userchk with the appropriate definitions of vorticity and work arrays > like > > common /scren/ vort (lx1,ly1,lz1,lelv,3) ! x y z components > $ , work1(lx1,ly1,lz1,lelv) > $ , work2(lx1,ly1,lz1,lelv) > > Let me check what we have for the calculation of strain tensor. > Best, > Aleks > > > On Wed, 13 Jul 2011, nek5000-users(a)lists.mcs.anl.gov wrote: > >> Hi, >> >> I need to calculate the vorticity vector and the rate of strain >> tensor at any >> arbitrary point in the domain. I wonder if these values are computed >> somewhere in the code or if I should interpolate them in the usr file. I >> appreciate any kind of help. >> >> Thanks in advance, >> >> >> Regards, >> Alireza Karimi >> >> _______________________________________________ >> Nek5000-users mailing list >> Nek5000-users(a)lists.mcs.anl.gov >> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users > _______________________________________________ > Nek5000-users mailing list > Nek5000-users(a)lists.mcs.anl.gov > https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users > > > ------------------------------ > > _______________________________________________ > Nek5000-users mailing list > Nek5000-users(a)lists.mcs.anl.gov > https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users > > > End of Nek5000-users Digest, Vol 29, Issue 2 > ******************************************** > -- Alireza Karimi PhD Candidate Department of Engineering Science and Mechanics Virginia Polytechnic Institute and State University Blacksburg, VA 24061

1 3

Error in generalev
by nek5000-users＠lists.mcs.anl.gov 02 Jul '14

02 Jul '14

Hello Neks, I've recently come across an error I haven't seen before. It occurs in the routine "generalev" at the beginning of my run. It looks like the matrix "a" and "b" being fed to the routine have an Infinity or NaN at position (0,0). Are there any ideas of what could cause this type of error? I have attached the logfile to this email. Thanks, -- Josh Camp "All that is necessary for the triumph of evil is that good men do nothing" -- Edmund Burke

1 11

Linearized Nek: Compute only the right-hand side
by nek5000-users＠lists.mcs.anl.gov 21 Jan '14

21 Jan '14

Hi Nek's, Given a random initial vector u and the Jacobian matrix of the linearized Navier-Stokes, I would like to calculate the matrix-vector product J * u. In Nek, that would consists in calculating only the right hand side of the equations, that is: RHS = ( -U.grad(u) - u.grad(U) - grad(p) + 1/Re Lap(u) ; div(u) ) I have a few questions on how to compute those different terms in userchk (Nek is used in post-process mode): - I would tend to use convop() for the convection terms, however I'm not sure whereas it would output the strong or weak form (and I need the strong one obviously)? - Same question regarding grad(p) and div(u) if I use opgradt() and opdiv() to calculate them? Last but not least, for the Laplacian I've read a previous mail where it is said that it can be computed using a sequence of wgradm1() and vec_dssum() so I guess I kown how to compute at the strong form for it. Sincerely, -- Jean-Christophe

1 4

problem with closed internal boundaries
by nek5000-users＠lists.mcs.anl.gov 23 Jul '13

23 Jul '13

Hello Neks, I'm trying to model a flow past an obstacle in a channel. As a first step I would like to do a 2D simulation. I'm encountering some problems during the geometry data generation in the nek5000 execution : it looks like the program can only generate NaN values although genmap seems to work well on the .rea file. I can also reopen the rea file with prenek without any problems. Do you have any idea what is going wrong here? Is it problematic to have a closed internal boundary condition? Thanks in advance for any help. Best, Michael B

1 9

opdiv and multd
by nek5000-users＠lists.mcs.anl.gov 10 Feb '13

10 Feb '13

Hi all, I am having some problems using the subroutines opdiv and multd. For some reasons they do not give me correct results. Do they need any special treatment or precautions? I was trying to compute the divergence of a 3D field, and i realized that in my case the multd subroutine used by opdiv does not gives good results, while the same derivative computed from gram1 gives no problems. For example, I overwrite an analytical field : ... parameter(lt=lx1*ly1*lz1*lelt) real Res(lt) ... vx(i,j,k,e)= 1.0*sin(x)*cos(y)*cos(z) ... call print_line(vx) ... iflg = 1 call multd (RES(1),vx,rym2,sym2,tym2,2,iflg) call print_line(Res(1) ) call gradm1(work1,Res(1),work2,vx) call print_line(Res(1) ) ... if (lx2.ne.lx1) then ... STOP endif and print output a (xr,:,zr) the result (performed by print_line) . In vxi.eps i compare the result (lines) with the analytical solution( symbols). The result of multd is not correct while all the others match perfectly the analytical solution. In vxy.eps i plot only the result of multd. Note that on y i have 12 elements the same number of peaks of the solution. Does anybody have an idea on how to fix this? Thank you very much for any help or suggestion francesco

1 14

Periodic B.C and Genmap Issue
by nek5000-users＠lists.mcs.anl.gov 09 Nov '12

09 Nov '12

Hi Paul, This post is in reference to the previous post by Michael (dated Jun 22). When I try to get a map file for a rea file that has periodic vertices, I get the following error. The rea file was generated the same way as before (Gambit -> Nek through Matlab). I checked on Matlab by plotting the periodic vertices and confirmed for a few faces that they are indeed periodic. Also, as you had earlier suggested (with the new genmap), I tried changing the tolerances fro 0.09 to 0.2 and I get the same periodic mismatch error. Could you provide any leads on where things are going wrong ? Please find below the error message. Thanks. <error> Input (.rea) file name: domain Input mesh tolerance (default 0.2): NOTE: smaller is better, but generous is more forgiving for bad meshes. 0.09 reading .rea file data ... start locglob_lexico: 8 3912 31296 8.99999999999999967E-002 locglob: 1 1 31296 locglob: 2 36 31296 locglob: 3 1224 31296 locglob: 1 4851 31296 locglob: 2 4851 31296 locglob: 3 4851 31296 locglob: 1 4851 31296 locglob: 2 4851 31296 locglob: 3 4851 31296 done locglob_lexico: 4851 4851 31296 10 start periodic vtx: 3912 4851 abort: PERIODIC MISMATCH 2: 1093 1 P ie 0 1 je 4.14470000000000029E-003 0.0000000000000000 bc 8 quit </error> Regards Shriram

1 10

Lagrangian Particle Tracking
by nek5000-users＠lists.mcs.anl.gov 22 Mar '12

22 Mar '12

Hi, I have couple of questions regarding the subroutine given for Lagrangian particle tracking at the following wiki page and I wonder if there are any hints. http://nek5000.mcs.anl.gov/index.php/Data_processing_example - Where should this subroutine be inserted? - What are the variables "rtl" and "mr" representing? - How to set the initial positions of the particles? - Should the constant parameters "npart" and "dt_p" be inserted in SIZE file? Thanks in advance, Regards, Alireza Karimi

1 3

Symetric / Antisymetric boundary conditions
by nek5000-users＠lists.mcs.anl.gov 29 Nov '11

29 Nov '11

Hi Nek's, I am currently investigation the linear stability of a symetric base flow using the linearized perturbation mode. As a matter of fact, I meshed only half the domain and used the appropriate symetry boundary conditions. Up to now, I was intesrested only in its stability with respect to symetric perturbations and thus had no problem. However, I am now interested in its stability with respect to antisymetric perturbation and I was wondering if there is any relatively simple way to implement such condition? Regards, -- Jean-Christophe

1 2

Calculation of Divergence Term
by nek5000-users＠lists.mcs.anl.gov 18 Nov '11

18 Nov '11

Hi, I want to solve an advection-diffusion equation in conjunction with the momentum and mass conservation equations. But my equation has an extra divergence term which I don't know how to calculate it in Nekton. So, denoting the scalar concentration field with c and velocity field with u, the equation turns out to be: dc/dt + u.grad c = Laplacian c - div (c V) which by d/dt I mean partial derivative with respect to time. V is a known vector field calculated from the vorticity tensor. I wonder if you could show me how to evaluate this additional term (the last term) in the user file. Best Regards, Alireza Karimi

1 17

Convective Outflow BCs
by nek5000-users＠lists.mcs.anl.gov 07 Nov '11

07 Nov '11

Hi I was looking for some information on convective outflow boundary conditions in nekton, I wonder if one can use such boundary conditions in nekton, and if so, if you could provide some information on how they are implemented in nekton. Regards Armin

1 1