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Showing results 1 to 11 of 11 Search took 0.00 seconds. Search: Posts Made By: joern

Forum: OpenFOAM Running, Solving & CFD April 22, 2010, 09:33

Replies: 61 Courant Number become bigger and bigger!!! Views: 11,843 Posted By joern icoFoam is no steady-state solver so you will not... icoFoam is no steady-state solver so you will not get an "convergence" state. you can control the initialResidual outputs of the linear solvers. they give a hint how much happens in one timestep.

Forum: OpenFOAM Running, Solving & CFD April 22, 2010, 08:30

Replies: 61 Courant Number become bigger and bigger!!! Views: 11,843 Posted By joern if it takes to many steps, try a coarser mesh. ... if it takes to many steps, try a coarser mesh. but if your mesh is too fine you need smaller timesteps, thats normal. are you sure about your max. velocity? i dont know the eigenvalues of the...

Forum: OpenFOAM Running, Solving & CFD April 22, 2010, 03:38

Replies: 61 Courant Number become bigger and bigger!!! Views: 11,843 Posted By joern ok, you'r right. but for icoFoam (like... ok, you'r right. but for icoFoam (like simplefoam) a use of Central Schemes lead to da central method. @bephi: a maxconum of 7 is now problem as long as your solution is ok ^^ take a look at the...

Forum: OpenFOAM Running, Solving & CFD April 21, 2010, 09:16

Replies: 61 Courant Number become bigger and bigger!!! Views: 11,843 Posted By joern the max-conum should not be much larger than 1... the max-conum should not be much larger than 1 because the discretisation of OF ist just semi implicit. the decoupling in OF causes explicit factors. In my test cases (for my diploma thesis) the...

Forum: OpenFOAM Running, Solving & CFD April 21, 2010, 05:25

Replies: 61 Courant Number become bigger and bigger!!! Views: 11,843 Posted By joern hi bephi, try to use bounded schemes like... hi bephi, try to use bounded schemes like "upwind" or a TVD-Scheme for the div-schemes. i think the convective terms produce an unbounded solution so you have to limit them. icofoam solves the...

Forum: OpenFOAM Running, Solving & CFD September 11, 2009, 06:20

Replies: 61 Courant Number become bigger and bigger!!! Views: 11,843 Posted By joern sandrak, what you discribe is a problem of... sandrak, what you discribe is a problem of rhosonicfoam. the solver is a "direct" solver for the decoupled euler-equations. if you use Ma 2 as speed the shockwaves all point into your domain,...

Forum: OpenFOAM Running, Solving & CFD September 10, 2009, 08:24

Replies: 61 Courant Number become bigger and bigger!!! Views: 11,843 Posted By joern sandrak, plese give some more info. what are... sandrak, plese give some more info. what are your BCs? what is your U? how is your start CoNum? what are your initial values? what schemes do you use? 1. rhoSonic is just stable for Ma>2....

Forum: OpenFOAM Running, Solving & CFD June 17, 2009, 09:11

Replies: 61 Courant Number become bigger and bigger!!! Views: 11,843 Posted By joern ok, i never used 'totalpressure', but... ok, i never used 'totalpressure', but 'fixedValue' is wrong. for mu=0 the sonicFoam solver solves the Euler-Equations. These Equations have the eigenvalues v-c, v and v+c. For a supersonic flow...

Forum: OpenFOAM Running, Solving & CFD June 16, 2009, 16:41

Replies: 61 Courant Number become bigger and bigger!!! Views: 11,843 Posted By joern did you just change Cv and nothing else? if... did you just change Cv and nothing else? if you just set up Cv and don't change R and U, then you get a completely different case. with Cv the speed of sound is defined as: c=sqr(R*p/rho*Cv +...

Forum: OpenFOAM Running, Solving & CFD April 23, 2009, 14:43

Replies: 61 Courant Number become bigger and bigger!!! Views: 11,843 Posted By joern if the coNum gets bigger and bigger it has... if the coNum gets bigger and bigger it has nothing to do with variable timestepping. if the solver isnt stable with very low deltaT then it wouldn't be stable for variable timestepping, either....

Forum: OpenFOAM Running, Solving & CFD April 22, 2009, 06:06

Replies: 61 Courant Number become bigger and bigger!!! Views: 11,843 Posted By joern as i posted in my thread: 1. check your... as i posted in my thread: 1. check your boundary conditions. fixedValue for U and p at the inlet lets the firtst cells "explode" (U=4e25 after some iterations) 2. try to use bounded...

Showing results 1 to 11 of 11

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