May 2014 - 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

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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

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Checking convergence to steady solution
by nek5000-users＠lists.mcs.anl.gov 02 Jun '14

02 Jun '14

Hello neks I am computing flow past 2d cylinder at Re=100. To get steady solution I run the unsteady solver with selective frequency damping. Looking at the forces on the cylinder and visualizing the solution I can see that I am getting a steady solution. But I would like to also quantitatively measure the convergence to the steady state. Is there a way that I can compute some residual to measure convergence to steady state ? Thanks praveen

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Questions in AXHELM and WLAPLACIAN
by nek5000-users＠lists.mcs.anl.gov 01 Jun '14

01 Jun '14

Dear nek5000 team, Could you help me with the 2 questions below? Thank you very much ! 1) Concerning the routine “axhelm” in hmholtz.f. If I am right, one possibility of this routine can be the discretisation of the diffusion operator. However it is not clear to me if axhelm performs: a) vdiff x Laplacian(phi) or b) grad ( vdiff x grad (phi) ) phi being the variable solved for (T or PS for example). So, is it actually a) or b) ? 2) In the routine wlaplacian in navier1.f, I am not sure to understand the consequence of the line: call sub2 (out,wrk,ntot) after the lines: call bcneusc(out,1) call axhelm(wrk,a,diff,h2,imesh,1) If I am right, this will change the sign in front of the diffusion operator, right? Because in makeq.f, I am not sure that the line call add2(bq(1,1,1,1,ifield-1),w1,ntot) will actually assemble the RHS of the transport equation : - (vtrans) x U grad (phi) + grad ( vdiff x grad (phi) ) Thank you for your help ! Best regards, Emmanuel

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How to add Coriolis force
by nek5000-users＠lists.mcs.anl.gov 31 May '14

31 May '14

Dear Neks; I want to add Coriolis force to do a rotating simulation. As known, the Coriolis term is defined as 2*omega(cross product)U, so how can I add it to the N-S equation? Is there any example of similar case? Thank you Xianbei

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About LELGEC in 'SIZE' file
by nek5000-users＠lists.mcs.anl.gov 30 May '14

30 May '14

In turbChannel example, the 'SIZE' file, line 44, a note reads'Note: In the new code, LELGEC should be about sqrt(LELG)', in this example,lelg=520(line 20), while, 'LELGEC=1' (line 46), so is the version of code not the new code? I have just downloaded it from the official site.

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strange output-duplicate points
by nek5000-users＠lists.mcs.anl.gov 30 May '14

30 May '14

Hi,all: I run the turbChannel example, and find a strange thing related to output. In the means.dat, #time = 8.0000000E+01 # y y+ Umean 0.000000000E+00 0.000000000E+00 0.000000000E+00 2.565198406E-03 1.235928661E+00 1.240919300E+00 8.166000752E-03 3.934430317E+00 3.853070992E+00 1.581402413E-02 7.619295888E+00 6.748781538E+00 2.418599733E-02 1.165296502E+01 8.841965326E+00 3.183402071E-02 1.533783060E+01 1.011635642E+01 3.743482305E-02 1.803633225E+01 1.084184821E+01 4.000002146E-02 1.927226091E+01 1.113974222E+01 4.000002146E-02 1.927226091E+01 1.113974222E+01 take a look at the last two lines, it's same! So the solver output the duplicate values, how can I correct this strange behaviour? Have a nice weekend Xianbei

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About the iobj in the drag calculation
by nek5000-users＠lists.mcs.anl.gov 29 May '14

29 May '14

Hi,all: I read Paul's reply in this mail https://lists.mcs.anl.gov/mailman/htdig/nek5000-users/2014-May/002756.html And got to know something about objects. As you say, the object is a collection of faces, here , I have a question about the iboj, how could I know which face it represent with iboj? As in turbChannel.usr, dragx_avg = alpha*dragx_avg + beta*0.5*(dragx(1)+dragx(2)) I think it means to do the time-average of the average dragx on planey1 and planey2, as 0.5*(dragx(1)+dragx(2)) indicates, while how to calculate the dragx on the planex1, planex2, planez1 and planez2? for the maxobj in this example is only 4 and dragx is defined as dragx(0:maxobj) Thank you Xianbei

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Problem w/ outflow and DIV(V)
by nek5000-users＠lists.mcs.anl.gov 29 May '14

29 May '14

Hello all, I am working on a problem consisting of an axially-horizontal cylindrical tank with an inlet (an opening) at its top and a connected pipe to its bottom as an outlet. The boundary conditions are set accordingly, i.e., inflow and outflow, respectively. Gravity is in vertical direction. I need to use Pn-Pn formulation as I use Moab for this problem. Assuming a steady-state condition with a full tank, this problem can be solved using single-phase NS solver. However, I noticed that there is large mass conservation error, as indicated by warning of "DIV(V)- QTL too large", when I run the case with a zero initial velocity field. I expected that this error decreased as the time evolved, but, it increased. Also a back-flow gradually starts to grow at the outflow boundary as well. I thought that this problem may be solved if I start from a realistic initial condition, however, it is not trivial for this problem. I am also skeptical about the zero pressure BC which is imposed at the outflow in Pn-Pn formulation. The other solution might be having an inlet (but outward) velocity at the outlet. So I wondered if anyone can give me a hint on this problem or the solutions proposed. Thanks, Mohsen

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Effect of CFL number.
by nek5000-users＠lists.mcs.anl.gov 28 May '14

28 May '14

Dear Neks, I would like to know what is the effect of CFL number on a turbulence simulation in SEM. I use polynomial order of lx1 = 5 and lxd = 8 and get a C = 0.176 for a Re = 2000 with dt = 0.001 in pipe flow where I find a transition to turbulence. when I decrease my time step 'dt = 0.0001 ' further my pipe becomes fully turbulent for the same mesh. When I increase the order lx1 = 7 and lxd = 10, I find a completely steady solution, instead of a transition to turbulence. It would be nice what if some could please tell me what parameter determines the accuracy of the simulation in terms of a turbulent flow because I am not able to reproduce the result with a different mesh or with higher order. Thank you, Kamal

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