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What's the difference between a linear and a nonlinear solver?

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Old   February 4, 2010, 19:46
Default What's the difference between a linear and a nonlinear solver?
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Recently I met with these two names.

I think that should be an easy question. I search this forum but cannot find the answer. Could anyone answer that?
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Old   February 5, 2010, 08:11
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I think a non-linear solver uses a newton-raphson like iterative solver. That is at each iteration you need to find the jacobian of the solution matrix.

If the solution matrix is dependent on the the fluid states, example the pressure is dependent on the temperature field (typical compressible flow), you need this type of solvers. In that case you need to supply the equation of state.

In incompressible flow, the coefficient matrix are not strongly dependent on the (thermodynamic) states of the flow variables, so linear solvers suffices.

My 5 cents

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