Jane,

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Firstly, I decided not to use the normal vector for now. Since thenormal vector is 2D, i wasn't sure how to implement the rest so that itis a 'double' since my g (neumann condition vector) has 3 componentswhen the normal vector will only have 2?

`I'm not sure I understand this -- in 2 space dimensions, the normal`

`vector has 2 components; in 3 space dimensions, it has 3 components.`

I went back to the beginning - step-22 tutorial and started fromabsolute basics. Testing with 1D, i have started with exact solutionu=(0,-y^2)^T and p = y^3, ie purely vertical.

`I also don't understand this, I'm afraid: in d space dimensions, the`

`velocity vector has d components. So if you're in 1d, how come your`

`velocity vector has 2 components?`

Similarly...

Doing a manufacturedsolution type, i get the right hand side vector f = (0, 4+3z^2, 2z)^T.

`the right hand side has d components. I suspect you are here showing the`

`right hand side of the whole system, which should then have d+1`

`components (which in 1d should be 2, not 3).`

`Or do you want to suggest in all of this that you really have a`

`two-dimensional domain but that the flow is one-dimensional?`

with my solution, on a rectangular domain, i have no tangential stressesanywhere, no flux on sides (unit normal being (/pm 1,0)), and plus andminus (0, z^3 + 4z) at the top.

`Your domain is [0,1]^2, so I understand how there is no flux through the`

`bottom because there u=[0,0]. But how do you arrive at the flux you show`

`here? The velocity field is quadratic in z (y?), and so should the flux,`

`but you show something that is cubic with the distance.`

`If instead of 'flux' you really mean 'stress', then it should actually`

`only be linear in z since it involves the *derivative* of the velocity.`

Best W. -- ------------------------------------------------------------------------ Wolfgang Bangerth email: bange...@colostate.edu www: http://www.math.colostate.edu/~bangerth/ -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en

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