On Tue, Feb 27, 2018 at 9:48 AM, 吴家桦Gauvain <causegauv...@gmail.com> wrote:
> Still a long way to go... Would you please tell me how to view the "truth > solve" solution? > RBConstruction::truth_solve take an int argument. If that's negative then it doesn't plot. If it's positive then it plots the "truth solution" in the steady-state case. In the transient case, if you set the int to be 10, for example, then it will plot every 10th time step. I suggest you do some solves with truth_solve directly and look at the solution since that will allow you to set up specific parameters and do a solve and check that it looks right. Note that train_reduced_basis also calls truth_solve and it has the int argument set to -1 so that it doesn't plot anything. David P.S. As usual, make sure you're using a direct solver (e.g. MUMPS) during debugging to eliminate incomplete solver convergence as one possible source of problems. 2018-02-27 22:00 GMT+08:00 David Knezevic <david.kneze...@akselos.com>: > >> On Tue, Feb 27, 2018 at 8:55 AM, 吴家桦Gauvain <causegauv...@gmail.com> >> wrote: >> >>> Thanks for replying. >>> >>> I did omit the inertia terms in my PDE. Regarding the greedy convergence >>> of 7 parameter transient case, the maximum error bound decreases as usual, >>> from about 40000 to 0.00197 but the result is abnormal like what is >>> described in my first mail. In fact, 3 parameter (thermal conditions) >>> transient case works well and so does 7 parameter steady case. The problem >>> arises when I attempt to combine them together by replacing the assembly >>> function of the stiffness matrix in 3 parameter transient case with that of >>> 7 parameter steady case. >>> >> >> Sounds like you need to do some debugging... e.g. set parameters to have >> min=max and see if it's still abnormal, or view the "truth solve" solution >> or other things like that to try to identify where the problem is. >> >> David >> >> >> >> >>> 2018-02-27 21:21 GMT+08:00 David Knezevic <david.kneze...@akselos.com>: >>> >>>> On Tue, Feb 27, 2018 at 4:03 AM, 吴家桦Gauvain <causegauv...@gmail.com> >>>> wrote: >>>> >>>>> Hi all, >>>>> >>>>> I am trying to make a transient thermoelastic RB model. Both Internal >>>>> heat >>>>> flux and external heat exchange described by Newton's law of >>>>> cooling(Robin >>>>> boundary condition) are considered. It works well when the three >>>>> thermal >>>>> conditions (heat flux, heat transfer coefficient and ambient >>>>> temperature) >>>>> are chosen as parameters. However, abnormal results are observed when >>>>> the >>>>> material properties (Young's modulus, Poisson's ratio, thermal >>>>> expansion >>>>> coefficient and heat conductivity) are added as parameters: Three >>>>> displacement components remain 0 and the temperature increases >>>>> drastically >>>>> as the time goes by. What's more, I notice that the difference between >>>>> the >>>>> first and the second POD eigenvalues is extremely large: >>>>> >>>>> POD Eigenvalues: >>>>> eigenvalue 0 = 4.4536e+08 >>>>> eigenvalue 1 = 2.45303e-07 >>>>> ... >>>>> last eigenvalue = -1.90536e-07 >>>>> >>>>> The matrix assembly should not pose problem because it runs well in >>>>> steady >>>>> case and I simply copy the assembly functions without any modification. >>>>> Thus I am really confused and I cannot figure out where the problem is. >>>>> Could you give me some suggestions? Thanks a lot. >>>>> >>>> >>>> Good to hear that it works well in the steady case. >>>> >>>> Regarding the transient case, I have a few comments: >>>> >>>> - The default implementation for transient RB that is used in the >>>> examples is intended for parabolic PDEs, like the heat equation. I guess >>>> your PDE is parabolic since you omit the hyperbolic parts (i.e. the inertia >>>> terms) from the elasticity part of the system? >>>> >>>> - 7 parameters is quite a lot of parameters, so you may just be having >>>> trouble with greedy convergence? >>>> >>>> My main suggestion would be to try to get a simple transient problem >>>> working first, then add more complexity to it until you reach the problem >>>> that you're interested in, e.g. you could start with the heat equation and >>>> then add elasticity terms. >>>> >>>> Regards, >>>> David >>>> >>>> >>>> >>> >>> >>> -- >>> >> >> > > > -- > *吴家桦 Gauvain* > *Mobile:13316300622 <(331)%20630-0622>* > *Email:g <gauvai...@foxmail.com>auvain.wujia...@gmail.com > <auvain.wujia...@gmail.com>* > 中山大学中法核工程与技术学院学生 > Institut Franco-Chinois de l'Energie > Nucléaire, L'université Sun Yat-sen > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
