February 2018 - Nek5000-users - mailman3.cels.anl.gov

Re: [Nek5000-users] angular velocity to the mesh velocity
by nek5000-users＠lists.mcs.anl.gov 09 Feb '18

09 Feb '18

Sijo, The mv_cyl example is a 2-D moving body example. As for the mesh velocity, can you please be more specific? Marco From: Nek5000-users <nek5000-users-bounces(a)lists.mcs.anl.gov> on behalf of "nek5000-users(a)lists.mcs.anl.gov" <Nek5000-users(a)lists.mcs.anl.gov> Reply-To: "nek5000-users(a)lists.mcs.anl.gov" <Nek5000-users(a)lists.mcs.anl.gov> Date: Friday, February 9, 2018 at 8:56 AM To: nek5000-users <Nek5000-users(a)lists.mcs.anl.gov> Subject: [Nek5000-users] angular velocity to the mesh velocity Hi Neks, Its a long time that i came up with something. So here we go, SInce I was doinf the FSI of aero foil, I have to deal with 2 degrees of freedom (its a 2D case) one in vertical and another in angular direction about the elastic axis of the profile. I could code the vertical motion of the foil but before starting the angular motion I have some doubts. Is there anyway to give the angular velocities directly to the mesh velocities? Apart from the translational velocity components Or Do you want me to covert the angluar velocities into translational components and give to mesh velocities? Do you have any example with a body which is rotating? Thanks in advance Sijo GEORGE

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angular velocity to the mesh velocity
by nek5000-users＠lists.mcs.anl.gov 09 Feb '18

09 Feb '18

Hi Neks, Its a long time that i came up with something. So here we go, SInce I was doinf the FSI of aero foil, I have to deal with 2 degrees of freedom (its a 2D case) one in vertical and another in angular direction about the elastic axis of the profile. I could code the vertical motion of the foil but before starting the angular motion I have some doubts. Is there anyway to give the angular velocities directly to the mesh velocities? Apart from the translational velocity components Or Do you want me to covert the angluar velocities into translational components and give to mesh velocities? Do you have any example with a body which is rotating? Thanks in advance Sijo GEORGE

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Computing aerodynamic coefficients
by nek5000-users＠lists.mcs.anl.gov 09 Feb '18

09 Feb '18

Dear Neks: I have a file containing the lift and drag coefficient for a wing that was computed long back using NEK5000. The value of the aerodynamic coefficients look fine. Since computations were carried out for a very specific set of parameters we do not have any experimental or numerical result to check it against. The code that I am using presently for computing aerodynamic coefficients is slightly different from the one we used earlier. Can someone please take a look at the following snippet from earlier version of the code and check if it computes the right aerodynamic coefficients? Many thanks. Best wishes, NN. subroutine set_obj ! define objects for surface integrals c include 'SIZE' include 'TOTAL' integer e,f,eg nobj = 1 iobj = 0 do ii=nhis+1,nhis+nobj iobj = iobj+1 hcode(10,ii) = 'I' hcode( 1,ii) = 'F' hcode( 2,ii) = 'F' hcode( 3,ii) = 'F' lochis(1,ii) = iobj enddo nhis = nhis + nobj if (maxobj.lt.nobj) call exitti('increase maxobj in SIZE$',nobj) nxyz = nx1*ny1*nz1 nface = 2*ndim do e=1,nelv do f=1,nface if (cbc(f,e,1).eq.'W ') then iobj = 1 if (iobj.gt.0) then nmember(iobj) = nmember(iobj) + 1 mem = nmember(iobj) eg = lglel(e) object(iobj,mem,1) = eg object(iobj,mem,2) = f c write(6,1) iobj,mem,f,eg,e,nid,' OBJ' c 1 format(6i9,a4) endif endif enddo enddo c write(6,*) 'number',(nmember(k),k=1,4) c return end

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[PhD proposal] Instabilities and transition to turbulence of time-periodic flows
by nek5000-users＠lists.mcs.anl.gov 09 Feb '18

09 Feb '18

Dear Nek's, Please find attached a PhD proposal on *instabilities and transition to turbulence of time-periodic flows* using Nek 5000. In a nutshell: building on previous work done at DynFluid (ENSAM, Paris, France), the PhD candidate will have to develop (among other things) a Newton-like solver in Nek5000 to compute unstable periodic orbits and to study their stability using Floquet stability theory. One of the possible flow configurations to be studied is that of the three-dimensional shear-driven cavity flow. The position starts early September/October 2018 In Paris, France. A three-year grant has been provided by the French Ministry of Higher-Education and Research to cover the wage of the PhD candidate. I would be very grateful if you could forward this PhD proposal to students of yours who would be interested. Best regards, Jean-Christophe Loiseau -- Jean-Christophe Loiseau Homepage <https://sites.google.com/site/loiseaujc/>

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DNS of turbChannel
by nek5000-users＠lists.mcs.anl.gov 08 Feb '18

08 Feb '18

Dear Nek users, I am new to NEK5000. I am aware of that two SGS models are available for the turbChannel. But if I am looking for a DNS, which line/subroutine shall I deactivate? Thanks a lot for the help. Regards, Emily

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Re: [Nek5000-users] Getting planar average and outputting data
by nek5000-users＠lists.mcs.anl.gov 08 Feb '18

08 Feb '18

Hi Jon, There is a set of new planar averaging routines that will merged into the repo soon.. these routines work for box type meshes (ex: meshes made using genbox since they have lexicographic element numbering). If you have a mesh that was made using genbox, you can use these routines from here: https://github.com/Nek5000/Nek5000/pull/411 Let me know if you have any questions about the usage of these routines. Ketan

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Rotating foil
by nek5000-users＠lists.mcs.anl.gov 08 Feb '18

08 Feb '18

Hi Neks, Its a long time that i came up with something. So here we go, SInce I was doinf the FSI of aero foil, I have to deal with 2 degrees of freedom (its a 2D case) one in vertical and another in angular direction about the elastic axis of the profile. I could code the vertical motion of the foil but before starting the angular motion I have some doubts. Is there anyway to give the angular velocities directly to the mesh velocities? Apart from the translational velocity components Or Do you want me to covert the angluar velocities into translational components and give to mesh velocities? Do you have any example with a body which is rotating? Thanks in advance Sijo GEORGE PhD student Ecole centrale de Nantes

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rotation of aero foil
by nek5000-users＠lists.mcs.anl.gov 07 Feb '18

07 Feb '18

Hi Neks, Its a long time that i came up with something. So here we go, SInce I was doinf the FSI of aero foil, I have to deal with 2 degrees of freedom (its a 2D case) one in vertical and another in angular direction about the elastic axis of the profile. I could code the vertical motion of the foil but before starting the angular motion I have some doubts. Is there anyway to give the angular velocities directly to the mesh velocities? Apart from the translational velocity components Or Do you want me to covert the angluar velocities into translational components and give to mesh velocities? Do you have any example with a body which is rotating? Thanks in advance Sijo GEORGE PhD student Ecole centrale de Nantes

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Getting planar average and outputting data
by nek5000-users＠lists.mcs.anl.gov 06 Feb '18

06 Feb '18

Dear Neks, I am trying to average a box geometry along the xz-plane using the planar_average_s subroutine from turbChannel. But it is not outputting all the y values from my domain. I am using the average file from avg_all as a restart file and hope to output the planar averaged velocity and passive scalars along the y direction. Could someone help me fix my code? Below is what I have so far: call planar_average_s(yy,ym1,w1,w2) call planar_average_s(uavg_pl,vx,w1,w2) call planar_average_s(vavg_pl,vy,w1,w2) call planar_average_s(wavg_pl,vz,w1,w2) call planar_average_s(tavg_pl,t(:,1,1,1,1),w1,w2) call planar_average_s(ttavg_pl,t(:,1,1,1,2),w1,w2) call planar_average_s(tttavg_pl,t(:,1,1,1,3),w1,w2) if(nid.eq.0) then open(unit=57,file='mean_prof.dat') do i=1,ny1*nely/2 write(57,3) yy(i) & , uavg_pl(i) & , vavg_pl(i) & , wavg_pl(i) & , tavg_pl(i) & , ttavg_pl(i) & , tttavg_pl(i) enddo 3 format(7f17.9) close(57) endif call exitt Thanks for any help, Jon

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Questions regarding avg_all
by nek5000-users＠lists.mcs.anl.gov 04 Feb '18

04 Feb '18

Hi all, I understand that a call to avg_all computes the running averages of u, u^2 etc and then dumps the results after a fixed timestep as given by param68. What I do not understand is where in the domain does this computation take place? Does it average all the points in the domain? I understand how this would by useful in the turbChannel case where fully developed turbulence covers essentially the entire domain. However in cases where the flow develops turbulence within the domain and thus there are strong regions of turbulent anisotropy, it would be imperative to calculate these running averages along a specified plane or line. I did see some code defining these in the turbChannel example viz. common /plane/ uavg_pl(ly1*lely) $ , urms_pl(ly1*lely) $ , vrms_pl(ly1*lely) $ , wrms_pl(ly1*lely) $ , uvms_pl(ly1*lely) $ , yy(ly1*lely) $ , w1(ly1*lely),w2(ly1*lely) $ , ffx_avg, dragx_avg but I'm not exactly sure how this is defining a particular section of the geometry. In my particular case I'm trying to simulate a rectangular jet exhausting into a cuboidal domain. How can I set avg_all to compute the said average along a streamwise plane of the jet for example? Sincerely, -- *Amitvikram Dutta* Graduate Research Assistant Fluid Mechanics Research Lab Multi-Physics Interaction Lab University of Waterloo

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