Discussion Forum

Posted: 1 decade ago Jul 18, 2010, 5:01 p.m. EDT

[QUOTE] hi Im trying to model the "obstacle in fluid" (3D) by using the graphical user interface in the help disk...I did all the step as the help,but I got this error when click the solve button: "Error: 7220 All variables solved for must be treated in at least one segregated solver step." do enyone know where is the problem? any help please... THANX maral [/QUOTE] Check the variables you're solving in the solver manager. Now, you have to list them all in the segregated solver manager, or it will give that error. Pay special attention to the lagrange multipliers (lm3,...). Also, please keep in mind that obstacle in the flow is a weakly coupled FSI problem (and not a two way strongly coupled FSI) in Comsol 3.5a AFAIK and remember.

Posted: 1 decade ago Jul 19, 2010, 12:17 a.m. EDT

hi Danial I dont know how to make this changes..I didnt find it in the solver manager and solver parameter... please tell me how to make these changes to get solution. Danial where can I found a good example then?I wanted to learn this model(obstacle in fluid) and use it in my own simulation(modeling 3D blood flow)..so u tell that I can not rely on this tutorial?what should I do to learn FSI then...I mixed up... Would you please help me Danial? god bless you maral

Posted: 1 decade ago Jul 19, 2010, 3:57 a.m. EDT

[QUOTE] hi Danial I dont know how to make this changes..I didnt find it in the solver manager and solver parameter... please tell me how to make these changes to get solution. Danial where can I found a good example then?I wanted to learn this model(obstacle in fluid) and use it in my own simulation(modeling 3D blood flow)..so u tell that I can not rely on this tutorial?what should I do to learn FSI then...I mixed up... Would you please help me Danial? god bless you maral [/QUOTE] Salam Maral, First, which version are you using? Comsol 4 or 3? I did not mean it is a bad example. It is quite good as it is. It's just that you should know which type of FSI coupling it has. Take a look at the boundary conditions for the flow e.g. and you will see that the structure movement does not affect flow velocity around the boundary (valid if you want to do stationary simulations not transient). Of course these are my interpretations. One very good example of two way FSI is the MEMS module fluid-structure-interaction.mph (you can find it in model library on this website as well). You don't need MEMS for it though and can solve it with Chemical Engineering module as well.

Posted: 1 decade ago Jul 19, 2010, 6:41 a.m. EDT

salam Im very thankful for your discription.. Danial Im using version 3.5.Would you please tell me how to make changes to remove that error? Its your kindness. maral

Posted: 1 decade ago Jul 19, 2010, 7:56 a.m. EDT

[QUOTE] salam Im very thankful for your discription.. Danial Im using version 3.5.Would you please tell me how to make changes to remove that error? Its your kindness. maral [/QUOTE] Look at the A window. Every variable there is listed in the B window. Don't miss any of them. You may see some lm3, lm4, ... when you enable the weak formulation. You should add them as well to the B side.

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Posted: 1 decade ago Jul 19, 2010, 9:26 a.m. EDT

THANK YOU VERY VERY MUCH DANIAL...you are so cool...