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FacetTangents() implementation

+3 votes

Hello,

I am trying to assemble numerical fluxes in 3D DG framework for which I need access to tangent vectors of the tetrahedral facets similarly to normal vectors implemented via the class FacetNormal(). Essentially I only need one tangent vector, defined on each facet as a vector pointing, e.g., from local vertex 0 to local vertex 1. Looking over the source code suggests that this feature is not yet supported by FEniCS, but is there an alternative way to define tangent vectors compatible with assembly process?

Thank you

asked Jan 9, 2015 by romant FEniCS Novice (150 points)

If you want to have access to tangential components of a quantity, you can always as well subtract the normal components from the original quantity.

commented Jan 9, 2015 by Christian Waluga FEniCS Expert (12,310 points)

Thanks for your hint Christian. I ended up rewriting the fluxes using double cross products.

commented Jan 14, 2015 by romant FEniCS Novice (150 points)
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