- **Main CFD Forum**
(*http://www.cfd-online.com/Forums/main/*)

- - **Linearization and continuation for upwind FVM schemes**
(*http://www.cfd-online.com/Forums/main/108133-linearization-continuation-upwind-fvm-schemes.html*)

Linearization and continuation for upwind FVM schemesHello all,
The question in short: Is it common to get a discontinuous Jacobian at steady state solutions when using upwind schemes and what can be done about it? The long version: I have a time-dependent advection-diffusion-reaction problem in one dimension which I need to be able to: 1) simulate 2) linearize 3) compute a steady-state mapping for a varying parameter. I first tried out the simplest thing I could think of (MOL with a first-order finite-difference scheme for spatial discretization) which turned out to be unstable. After some study, I ended up with implementing a first order upwind finite volume method. This model is stable and I can perform simulations. However, I run into problems with linearization. Since the advective flow can switch sign in the problem, it was necessary to introduce logic for the upwind-scheme. This in turn cause the Jacobian to become discontinuous at the steady-state solution. Is this a common problem and how do I solve it? One of the reasons I need to linearize is that I want to use continuation in order to compute the steady-state mapping between some states and a control-parameter. Due to the discontinuity, the nullspace of the Jacobian get too many dimensions which cause my continuation algorithm to fail... I'm now thinking about abandoning the FVM-method and try some collocation method for the spatial discretization. Do you think that is a feasible path? /Best regards Ps. I'm rather new to CFD so please, If you know any good litterature for advective-diffusive-reactive problems, I would greatly appreciate tips. |

All times are GMT -4. The time now is 00:58. |