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By default, the Convection check box is selected. Clear the check box to disable convective transport.
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Select the Migration in electric field check box to activate the migration transport of ionic species. See further the theory section Adding Transport Through Migration.
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Select the Dispersion in porous media check box to activate the dispersion mechanism in porous media. See further Dispersion in the theory chapter.
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Select the Volatilization in partially saturated porous media check box to model volatilization in partially saturated domains. See further Theory for the Transport of Diluted Species Interface.
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When the Crosswind diffusion check box is selected, a weak term that reduces spurious oscillations is added to the transport equation. The resulting equation system is always nonlinear. There are two options for the Crosswind diffusion type:
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Do Carmo and Galeão — the default option. This type of crosswind diffusion reduces undershoots and overshoots to a minimum but can in rare cases give equation systems that are difficult to fully converge.
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Codina. This option is less diffusive compared to the Do Carmo and Galeão option but can result in more undershoots and overshoots. It is also less effective for anisotropic meshes. The Codina option activates a text field for the Lower gradient limit glim. It defaults to 0.1[mol/m^3)/tds.helem, where tds.helem is the local element size.
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For both consistent stabilization methods, select an Equation residual. Approximate residual is the default and means that derivatives of the diffusion tensor components are neglected. This setting is usually accurate enough and is computationally faster. If required, select Full residual instead.
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ndflux_c (where c is the dependent variable for the concentration). This is the normal diffusive flux and corresponds to the boundary flux when diffusion is the only contribution to the flux term.
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ntflux_c (where c is the dependent variable for the concentration). This is the normal total flux and corresponds to the boundary flux plus additional transport terms, for example, the convective flux when you use the non-conservative form.
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