Re: [deal.II] step-22 compute_no_normal_flux_constraints

Hi Wolfgang Thanks for your reply. That was actually what I had done previously. I've tried all sorts by looking at the values on different boundaries, indicators, tried multiple problems, etc before I had asked the question, which is why I came to thinking it had something with the

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

Hi Wolfgang, I can get a table if it would be useful. I see what you mean in terms of convergence. I guess I was looking for the accuracy pointwise on a boundary where the Dirichlet condition for the pressure is imposed weakly. In my case, the value of the output on the boundary was

Re: [deal.II] step-22 compute_no_normal_flux_constraints

Still looking for any ideas as suggestions to this boundary condition problem! Thanks so much On Tuesday, March 26, 2019 at 11:27:02 AM UTC, jan...@jandj-ltd.com wrote: > > Hi Wolfgang, > > So this was why I couldn't figure it out. > > The mesh has over 10 cells in it, it is super refined.

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

As an update to this thread (please let me know if you think i should start a new one): I continued to find out why I wasn't getting the correct applied Dirichlet values on the boundary for a code very similar to step-20, where the Dirichlet condition is applied weakly using for (unsigned int

Re: [deal.II] step-22 compute_no_normal_flux_constraints

Hi Wolfgang, So this was why I couldn't figure it out. The mesh has over 10 cells in it, it is super refined. And oddly, when the refinement level is less, it doesn't blow up. It's only after a certain point. it is an even global refinement, starting from a hyper divided rectangle. no

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

Thanks Jean-Paul, I set n_components to dim and it ran. However, no difference whatsoever in the solution to when I was equivalently imposing in the weak form (where the tangential term disappears due to being zero), so I do continue to wonder whether the two are equivalent. Thank you On

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

In addition to above, I thought I'd try VectorTools::compute_ nonzero_tangential_flux_constraints: I did: std::set no_tang_flux_boundaries; no_tang_flux_boundaries.insert(1); const Functions::ZeroFunction no_tang_bcs; typename FunctionMap::type no_tang_map; no_tang_map[1] = _tang_bcs;

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

No that's fair enough. I had thought the way I was doing it would be the equivalent of setting no tangential stresses. I actually also did it this way as I wasn't sure how you impose it strongly. To impose strongly - would you just use

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

Hi Wolfgang, step-20: Yes indeed I do agree that that is what I am doing. I guess I'm trying now to find out what else it could be that is producing: the correct boundary points as in the Dirichlet condition when local_rhs=0 is done again (overwriting), but the wrong boundary points when it

Re: [deal.II] Finding the y-coordinate of the boundary during the assembly

This did exactly what I needed. Thanks!! On Saturday, March 16, 2019 at 5:48:14 PM UTC, Jean-Paul Pelteret wrote: > > There’s a function to compute the bounding box in GridTools: > > https://www.dealii.org/current/doxygen/deal.II/namespaceGridTools.html#ae1ec55abefa31cf001fd29d8d4d993f1 > > > On

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

Hi Wolfang, thanks for your time on this. Ok, re the first step-20 bc issue, I'll have another think, but I still am not sure why then it isn't giving me the exact figure, whilst my suggestion is (I understand your point here and I would have said I agreed with you, but my implementation does

Re: [deal.II] Finding the y-coordinate of the boundary during the assembly

Thanks for your suggestions. BoundingBox should for now be sufficient, but I am having some trouble using it properly. I am unsure what to put in to use it? triangulation? cell? I think i need something like BoundingBox mybox; mybox.get_boundary_points(); but I'm a little unsure where I put

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

So that's what I meant by having extra contributions. I thought you needed a local_rhs = 0 after/within: for (unsigned int face_n = 0; face_n < GeometryInfo::faces_per_cell; ++face_n) if (cell->at_boundary(face_n)) {

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

>What line of the code would that be? Do you think it would be wrong to just >*always* set local_rhs=0? Always setting local_rhs = 0 immediately before the below implementation would take into account all cases so that would be the best: for (unsigned int q=0;

Re: [deal.II] Finding the y-coordinate of the boundary during the assembly

Hi Jean Paul, Thanks for this - for now this should be sufficient, though for the rest I will have to do a long blurb. Do you have an example of how to use BoundingBox? I'm a little confused by the document. I don't know what i have to set for the argument before i do something (i am

Re: [deal.II] Finding the y-coordinate of the boundary during the assembly

Hi Wolfgang, Yes, what you put into much better words than mine is exactly what I am needing - For a given quadrature point at (x,y), find how far the domain extends above (x,y) in y-direction? So I am looking to find the y-coordinate of the point which is directly above the (x,y) in

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

Hi Wolfgang, I would think that it might be useful in the tutorial!! Please do let me know if you have any suggestions on a perhaps analogous question for step-22 in my other reply to this thread. I'm making the analogy between the dirichlet boundary condition implementation and the normal

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

Hi all, as an addition to this post, For Dirichlet condition that are in the weak form, would this have to be done? And for example, for an inhomogeneous normal component of the normal stress condition in step-22 for Stokes (1st of the partial bc discussion in the tutorial), do you also have

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

Note that I think this was the issue. You would need to put local_rhs = 0 within the part below to apply the Dirichlet condition. Please do let me know if you think this is wrong but I am getting the correct output. Thanks for (unsigned int face_no=0; face_no::faces_per_cell; ++face_no) if

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

Hi Wolfgang, Sorry for the reply - for some reason i didn't get the notification. What i mean by correct is that I do have two uncoupled equations, but that it is correct in that I had already verified it using what you suggested (by using exact solutions - MMS). By it fails, I mean that the

Re: [deal.II] Accuracy of Dirichlet condition for p in step-20

Hi Both, Thanks for your replies. Daniel, the weak forms are as in the steps, but with Neumann ocnditions on boundaries other than the top. With the chosen spaces, I believe the problem is well-posed. Wolfgang, so that's exactly what I had done with MMS, and that was verified, so i assumed

[deal.II] Re: Accuracy of Dirichlet condition for p in step-20

Hi all, Does anyone have any suggestions on this? I'm still struggling to get the values to equal more precisely. Thanks On Wednesday, February 6, 2019 at 7:22:28 PM UTC+3, jane...@jandj-ltd.com wrote: > > Hi all, > > I am trying to solve a system of equations that do this: > Stokes to solve

[deal.II] Accuracy of Dirichlet condition for p in step-20

Hi all, I am trying to solve a system of equations that do this: Stokes to solve for v_r and p_r for one fluid (viscous rock), I use these solutions on the RHS of a Darcy type equation solved like step-20 for the pressure p_f in the fluid in the domain. Using the 3 solutions, I update another

Re: [deal.II] cumulative displacement / deformation

Right ok, interesting. I see what you mean though I am confused how you got to the equation for the displacement? Surely there needs to be some time dependence somewhere at least for it to make sense dimensionally? On Sunday, October 14, 2018 at 11:19:33 PM UTC+1, Wolfgang Bangerth wrote:

[deal.II] cumulative displacement / deformation

hi all, I am solving some equations on a moving domain which essentially compacts. I am using something similar to that in step-18 to move my mesh around. So i have something like pcout << " Moving mesh..." << std::endl; std::vector vertex_touched (triangulation.n_vertices

Re: [deal.II] Inhomogeneous neumann bc for step-20

Hi Daniel, I did indeed have this in. I seem to have fixed it when I rewrote everything from scratch... seems sometimes it is quicker to start from the beginning. Thanks to all that helped - I have learned a great deal from this post alone and I hope I can contribute as much. On Saturday,

Re: [deal.II] Inhomogeneous neumann bc for step-20

k great - good to know that I am implementing it correctly. I'm not sure - I didn't think it would have mattered, but something seems to be going when you also have a Dirichlet condition application (My code works fine with Dirichlet all around the boundary). The values I am using are

Re: [deal.II] Inhomogeneous neumann bc for step-20

I've further run some tests with Dirichlet all around the boundary. I get a smooth p solution but a similar jump to the previous attachment but ONLY in the x component of u On Saturday, September 8, 2018 at 3:48:12 AM UTC+1, Wolfgang Bangerth wrote: > > > > With what you are saying with the

Re: [deal.II] Inhomogeneous neumann bc for step-20

Also, as additional comments (having run some more tests), The Dirichlet condition application is fine - I get the correct solutions and convergence rates when Dirichlet conditions are defined on the entire boundary. When u.n = u_known.n is applied everywhere, this doesn't give the correct

Re: [deal.II] Inhomogeneous neumann bc for step-20

Ok great - good to know that I am implementing it correctly. I'm not sure - I didn't think it would have mattered, but something seems to be going wrong with the Dirichlet condition application (when I remove that snippet of code, the solution is at least smooth). The values I am using are

[deal.II] Inhomogeneous neumann bc for step-20

Dear all, I am trying to solve the equations in step-20 with inhomogeneous neumann bcs on one of the boundaries and getting something very bizarre. I have a rectangular domain with the following: 1. Top boundary has homogeneous conditions: this is applied into the weak form like in step-20

Re: [deal.II] Adding to / changing domain at every timestep. merging mesh.

s fe_index to the one > corresponding to "FE_Something" in your FECollection. > > I hope my brief explanation was clear enough, and that this suggestion is > relevant for your problem. > If you ever need further information, don't hesitate to ask. > > Best, > > Claire &g

Re: [deal.II] interpolate different solutions on different parts of the domain

o’s suggestions is the > FEFieldFunction > <https://www.dealii.org/9.0.0/doxygen/deal.II/classFunctions_1_1FEFieldFunction.html> > class > possibly of any use to you in this situation? > > Best, > Jean-Paul > > On 31 Jul 2018, at 18:08, Bruno Turcksin > wrote: >

Re: [deal.II] Re: interpolate different solutions on different parts of the domain

). This i'm considering a problem as I have to redistribute my dofs once I have the new domain comprising domains 1 and 2. On Tuesday, July 31, 2018 at 5:08:50 PM UTC+1, Bruno Turcksin wrote: > > Le mar. 31 juil. 2018 à 11:49, Jane Lee > a écrit : > >> What i then have g

[deal.II] Re: Initialising vector solution for mixed formulation problem

Hi Daniel, Thanks for your reply, the error i was getting was: void dealii::VectorTools::interpolate(const Mapping &, const DoFHandlerType &, const Function &, VectorType &, const dealii::ComponentMask &) [dim = 2,

[deal.II] Initialising vector solution for mixed formulation problem

Hi all, I'm having a problem with trying to initialise a vector solution. Background: I am solving two systems of equations back to back repeatedly. I need the solution for the 2nd system to solve the first one at the next 'timestep', say. But initially/at the first 'timestep', I solve the

[deal.II] Re: error running after update

m. >>> How did you install deal.II? Are you using spack directly or a >>> pre-compiled package? >>> If you are using spack directly you should just rerun it to get a recent >>> developer version. >>> >>> Best, >>> Daniel >>>

[deal.II] error running after update

Hi all, I'm unfortunately not very good with computers and the nitty gritty details of the things that go on behind the program. I'm running dealii-9.0 instead of 8.5.1 because i did a system update and 8.5.1 wasn't working. I stupidly did a minor update forgetting that i had issues after

[deal.II] convergence when using get_function_gradients on a scalar field and problem degrees

Hi All, Just a quick question on convergence rates/error analysis. I have a solver which does primarily what they do in step-20. The model I am trying to solve takes the pressure solution from the equations in step-20 and uses its gradient on the right hand side of a new equation. I use

Re: [deal.II] Re: step-22 partial boundary conditions

Following this, note that using the stress as a tensor function produced the same results/problems (same errors too as doing it with component_i) but wouldn't have thought that would have made a difference anyway... On Monday, March 5, 2018 at 6:59:43 PM UTC, Jane Lee wrote: > > Hi Wo

Re: [deal.II] Re: step-22 partial boundary conditions

Hi Wolfgang, I believe the formula is correct. the cubic term comes from p=z^3 being the pressure manufactured solution. so in (pI-2e) you get a z^3 term and indeed a linear term in the 2e portion. The code commpiles and the error analysis is correct with Dirichlet conditions on the top and

Re: [deal.II] Re: step-22 partial boundary conditions

Hi Wolfgang, thanks so much for getting back to me 1. I was wondering re dimensions because I could find a component mask function or something similar to fe_values[velocities], eg, when using fe_face_values which you need to apply the neumann conditions. 2. This is my fault. I meant working

[deal.II] Re: step-22 partial boundary conditions

HI, I'm still looking for help with this problem. it would be much appreciated. thanks On Monday, January 15, 2018 at 11:39:16 PM UTC, Jane Lee wrote: > > Hi Wolfgang, happy new year and hope you had a good break. > > I'm back working on this and I just don't understand wha

Re: [deal.II] step-22 partial boundary conditions

Hi Wolfgang, right so in the Stokes subsystem of my equations, in simplified form I am trying to solve: div tau - grad p = rhs1 div v = rhs2 where my tau is 2 epsilon as in step-22 The boundary conditions I now want to implement to solve the 'real' problem is: on the sides (boundary 0): zero

[deal.II] Using FunctionMap for nonzero normal flux (eg in step-22)

I'm wondering whether I've misunderstood how to use the FunctionMap declaration. I'm needing it to use for VectorTools::compute_nonzero_normal_flux_constraints At the moment I am trying to apply nonzero normal component of the normal stress in step-22 on a boundary id that is 2 I have tried

Re: [deal.II] step-22 partial boundary conditions

Hi Wolfgang, Apologies but could you just clarify? I get that the stress boundary can be put into the weak form, but only really when you have Neumann conditions. And why would I have to use a compute_nonzero_normal_flux for a zero one? I believe it my have been my fault not being clearer.

Re: [deal.II] step-22 partial boundary conditions

algorithmically, what I was doing previously wouldn't work? Thank you - I will keep having a look mathematically if there is some manipulation I might be able to do. Many thanks On Monday, November 27, 2017 at 10:53:14 PM UTC, Wolfgang Bangerth wrote: > > On 11/27/2017 01:16 PM, Jane Lee wrote: &

[deal.II] step-22 partial boundary conditions

I'm trying to apply some partial boundary conditions to the step-22 stokes problem. I can't seem to find much further help on this and when I try and implement it, it solves but solution is clearly unstable/blows up. I am trying the basics before i impose inhomogeneous quantities, and using

[deal.II] help with get_function_divergences for a vector solution

Dear all, I am hoping someone can shed a bit more light on a problem I am having. The background of the system of equations i am solving: I have 4 DAEs (for pf, pr, vr, vf) and 2 time dependent equations (phi, t) as a system of 6 equations. I am solving the 4daes first then using the

Re: [deal.II] using VectorTools::interpolate_boundary_values :Simple verification of Stokes system with zero velocity (using step-22)

Thanks Wolfgang, very silly of me. Have sorted the other problem too which didn't have anything to do with the way i was interpolating boundaries. On Wednesday, February 1, 2017 at 6:30:00 PM UTC, Wolfgang Bangerth wrote: > > On 02/01/2017 11:24 AM, Jane Lee wrote: > > > >

Re: [deal.II] using VectorTools::interpolate_boundary_values :Simple verification of Stokes system with zero velocity (using step-22)

Hi Wolfgang, thanks for a swift reply. and apologies, I wasn't very clear. when I'm imposing dirichlet conditions everywhere, i don't have a condition for pressure (those were two separate test cases - sorry i was unclear). and i'm using: VectorTools::interpolate_boundary_values

[deal.II] using VectorTools::interpolate_boundary_values :Simple verification of Stokes system with zero velocity (using step-22)

Hi all, This may seem like a very obvious question/mistake on my part so please do excuse me if I've overseen something very simple. I'm trying to solve a stokes system with some funny boundary conditions so I've stripped the code to make sure I was getting the correct answers to a very