Thank you Martin, I will have a look at these solutions! Best regards, Helena
Martin Schneider <[email protected]> schrieb am Fr., 10. Feb. 2023, 08:13: > Dear Helena, > > if I understand you correctly, you want to calculate spatial gradients > of your primary variables? > This is not straight-forward for CCTPFA, at least if you have > heterogeneous data. > If you need the pressure gradient, you could recalculate it from the > darcy velocity and simply use the existing > velocity calculation in dumux > ( > https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/porousmediumflow/velocity.hh). > > > > There is also a more generic way to calculate gradients by using for > example equation (39) in > > https://ogst.ifpenergiesnouvelles.fr/articles/ogst/pdf/2018/01/ogst180050.pdf > There, K denotes the control volume (element) for which you want to > calculate the gradient of some primary variable u and u_\sigma is some > approximation of your solution on face \sigma (in Dumux denoted as scvf). > For CCTPFA u_\sigma can be calculated as the harmonic average of > neighboring solution values with corresponding transmissibilities. If > you have homogeneous data this would be simply some distance average. > > We are currently working on a generic way to interpolate variables and > to calculate gradients, however, this is not yet available. > > I hope this helps. > > Best regards, > Martin > > > On 09.02.23 20:06, Helena Kschidock wrote: > > Hi all, > > > > I am currently implementing a cell problem in DuMuX and am using an > > adapted 1p model/Darcy Problem with CCTPFA discretization to do so. > > After obtaining the solution vector, I need to obtain the gradients of > > the solution which I will then use to calculate my upscaled > > conductivities through integration. > > > > In the exchange with Dimitry Pavlov in the mailing list archive (see > > 2020q2 "How to implement MaterialLawParams that depend on pressure > > gradient"), Timo suggested using the Jacobian to obtain the gradients > > (which I could easily make available in my case, as the step is done > > AFTER solving the cell problem). However I am slightly confused - > > isn't the Jacobian the partial derivative of the residual with respect > > to the solution (instead of the partial residual of the solution with > > respect to the dimension)? At least this is what the handbook seems to > > imply. > > > > Thanks for any help, > > Helena > > > > _______________________________________________ > > DuMux mailing list > > [email protected] > > https://listserv.uni-stuttgart.de/mailman/listinfo/dumux > > >
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