Re: [deal.II] Question about the advice about regularity of the stokes' equations in Step-22

On 3/10/20 12:59 PM, Krishnakumar Gopalakrishnan wrote: Step-22 has a strong-sounding stub-like statement:/"In practice, one wants to impose as little regularity on the pressure variable as possible". / / / The above one-liner (fairly enough) assumes domain knowledge. As a new entrant to

Re: [deal.II] How to determine the saddle-point nature of PDEs like those in Step-20, 21?

I had seen that github issue/pull-request, but didn't realise that "saddle-point problems = (indefinite + symmetric)". These three words do not appear in close-proximity to each other anywhere in the slides, tutorials or video lectures. While I acknowledge the importance of mathematical

Re: [deal.II] How to determine the saddle-point nature of PDEs like those in Step-20, 21?

Dear Prof Bangerth. Thank you for your reply. I had seen that github issue/pull-request, but didn't realise that "saddle-point problems = (indefinite + symmetric)". These three words do not appear in close-proximity to each other anywhere in the slides, tutorials or video lectures. While I

Re: [deal.II] Re: solving stabilized Stokes

Dear Wolfgang, I spent some time re-reading the theory and you are right, nothing shows that the convergence rate should be conserved when we have stabilized equal order elements. However it is interesting to note that when we use stabilization and we revert to LBB stable elements (Q2-Q1 for

[deal.II] Re: solving stabilized Stokes

In addition to the above results. I ran the same MMS with the GLS stabilized solver but using Q2-Q1 and Q2-Q2. What i obtain for Q2-Q1 is exactly what you would expect: *Velocity* Cell error - 64 1.4972e-02- 256 1.9438e-03 2.95 1024 2.4542e-04 2.99 4096 3.0755e-05 3.00

Re: [deal.II] How to determine the saddle-point nature of PDEs like those in Step-20, 21?

On 3/11/20 7:57 AM, Krishnakumar Gopalakrishnan wrote: In Step-21 tutorial, we have a statement that starts with the following (emphasis is mine): /_"Given the saddle point structure_ of the first two equations and their similarity to the mixed Laplace formulation we have introduced in

Re: [deal.II] Updated link to Jack Poulson's PhD thesis (in the landing page of video lecture 34)

On 3/10/20 11:43 AM, Krishnakumar Gopalakrishnan wrote: The link to Jack Poulson's text currently in the landing page of Video Lecture 34 https://www.math.colostate.edu/~bangerth/videos.676.34.html has become out of date. For the

Re: [deal.II] Re: solving stabilized Stokes

On 3/11/20 8:54 AM, Bruno Blais wrote: Q1-Q1 using the GLS (SUPG +PSPG) stabilized solver of Lethe using a monolithic iterative solver and Q2-Q1 using the Grad-Div solver with a Schur completement solution strategy (similar to step-57 but using Trilinos). *Here are the results I obtain:*

[deal.II] Re: solving stabilized Stokes

Dear Richard, Thanks for your message! It is very interesting. Your results made me doubt our own results, so I re-ran Error convergence analysis on a manufactured solution ( an infinitely continuous one) where the domain is bounded by purely Dirichlet boundary condition. I did the simulations

[deal.II] How to determine the saddle-point nature of PDEs like those in Step-20, 21?

In Step-21 tutorial, we have a statement that starts with the following (emphasis is mine): *"Given the saddle point structure of the first two equations and their similarity to the mixed Laplace formulation we have introduced in step-20

[deal.II] Re: Matrix-free: Continuous elements and boundary (face) integrals

I tried to fix that by myself, but I could not locate the source code of MatrixFree::internal_reinit W dniu poniedziałek, 9 marca 2020 14:20:16 UTC+1 użytkownik Michał Wichrowski napisał: > > Deal all, > I want to weakly impose boundary conditions on, let's say, Laplace problem > (in fact I'm