Dear Martin,

We apply a number of static condensation techniques to help reduce the matrix size in this solver. We do not typically therefore ever really construct the full matrix. 

One way of extracting the full matrix however (for small problems) would be to set a value of 1 in the m_coeffs array and then call the solve. Then repeat this operation for every entry in the matrix.  Strictly speaking we should only really put a 1 in the array when it is in global storage pattern so it may also be necessary to set up a global array, put 1 an entry of this array,  Call GlobalToLocal() use the output of GlobalToLocal to call the Linearised Navier-Stokes solver. On output the Linearised Navier-Stokes operator will give you the array in Local coefficient space and so you may also need to call LocalToGlobal() on this array.

Sorry there is not a more straight forward approach.

Cheers,
Spencer.

On 25 Jan 2017, at 07:58, Martin Hess <mhess@sissa.it> wrote:



Dear All,

I would like to use the incompressible Navier-Stokes solver for parametric model order reduction.

As a first step, I thought I have a look at the assembled system matrix in the steady stokes case, since
I need access to these matrices in some point. What I found in the code are several layers of static condensation,
but no access to the complete linearised Navier-Stokes element matrix.

Could I somehow form that matrix from the available submatrices formed in CoupledLinearNS.cpp?

Best,
Martin Hess




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Spencer  Sherwin
McLaren Racing/Royal Academy of Engineering Research Chair, 
Professor of Computational Fluid Mechanics,
Department of Aeronautics,
Imperial College London
South Kensington Campus
London SW7 2AZ

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