Hi Felix,
the derivatives are currently only used inside the laws themselves, particularly for the regularization. See for example the pc function in regularizedvangenuchten.hh. There, the function VanGenuchten::dpc_dswe is called to determine the correct slope of the regularized curve. If you implement your own law, you don't need the derivative functions since they are never called from outside. One could use the derivative functions to calculate analytical derivatives for the Jacobian matrix, but this hasn't been done so far. Maybe a clean approach for the future would be to remove these functions from the interface. Kind regards Bernd -- _______________________________________________________________ Bernd Flemisch phone: +49 711 685 69162 IWS, Universität Stuttgart fax: +49 711 685 60430 Pfaffenwaldring 61 email: [email protected] D-70569 Stuttgart url: www.hydrosys.uni-stuttgart.de _______________________________________________________________ ________________________________ Von: Dumux <[email protected]> im Auftrag von Felix Feldmann <[email protected]> Gesendet: Montag, 17. Juni 2019 15:18:16 An: DuMuX User Forum Betreff: [DuMuX] Fluidmatrix interactionlaws - partial derivatives Dear DuMux developer, Looking at the fluidmatrixinteractionlaws, I do find the implementation of several partial derivatives. For example, in case of the BrooksCorey model: • The derivative of the relative permeability for the non-wetting phase in regard to the wetting saturation dkrn_dswe() • The derivative of the relative permeability for the wetting phase with regard to the wetting saturation dkrw_dswe() • The partial derivative of the capillary pressure w.r.t. the effective saturation dpc_dswe() • The partial derivative of the effective saturation w.r.t. the capillary pressure dswe_dpc() I don’t really understand the purpose of the derivatives. In case I remove them, my code is still running fine and is given me the identical result. However, since I am currently implementing a modified fluidmatrixinteractionlaw, I would like to understand the purpose of the derivatives. Unfortunately, in this case, the DuMux Handbook as well as the online documentation provides quite limited information. Best regards, Felix -------------------------------- Felix Feldmann Research Assistant [cid:[email protected]] SAN Campus P O Box 2533, Petroleum Institute Abu Dhabi, UAE M +971 565624402 [email protected]<mailto:[email protected]>
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