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

bearcat · February 4, 2010, 19:46

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?

taw · February 5, 2010, 08:11

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

Cheers

February 4, 2010, 19:46	What's the difference between a linear and a nonlinear solver?	#1
bearcat Member bearcat Join Date: Jul 2009 Location: Ohio Posts: 35 Rep Power: 17	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?

February 5, 2010, 08:11		#2
taw New Member Join Date: Oct 2009 Posts: 29 Rep Power: 17	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 Cheers granzer likes this.

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