How to set a slip boundary.

[Benxi]

Hello Everyone. rnWhen i use the OpenLB, i find a question.rnFor example, when i use the class template superGeometry.rename() to change the geometry boundary, i can set 1 for fluid, 2 for no-slip boundary, 3 for velocity boundary, 4 for constant pressure boundary, 5 for cureved boundary, 0 for nothing. rnIf the boundary is a slip boundary,(because my simulation model is a part of big fluid region) how can i set it?rnI have tried the SlipBoundaryProcessor2D to generate the boundary and compiling success and running failed which showed a lot of message like “”no boundary found at (20,64) ~ (0.9,3.1), in direction 3″”. How can i solve it?rnYour sincerely, Benxi

[lilianaxavier]

Hi,rnrnyou can use the slip boundary condition in a similar way as you use a velocity or pressure boundary conditions.rnYou can set as “”addSlipBoundary”” on the material number you desire to have this type of BC.rnrnBest regards.

[Benxi]

Quote:

Quote from lilianaxavier on May 12, 2016, 14:10rnHi,rnrnyou can use the slip boundary condition in a similar way as you use a velocity or pressure boundary conditions.rnYou can set as “”addSlipBoundary”” on the material number you desire to have this type of BC.rnrnBest regards.

rnrnHi!rnThank you for your reply and these days i have tried a lot of way and finally get it work now.rnFrom the fluid region graph i get, i think the addSlipBoundary function work well now ,but when i run my program as ./Program_name, the command window shows the warning as follow:rnWARNING: Bogus distance at (22,88): 1rnWARNING: Bogus distance at (21,88): 1rnWARNING: Bogus distance at (21,87): 1rnWARNING: Bogus distance at (21,86): 1rnWARNING: Bogus distance at (33,62): 1rnWARNING: Bogus distance at (34,62): 1rnrnrn[BoundaryConditionInstantiator2D] Warning: Could not addSlipBoundary (2, 118), discreteNormal=(0,0,0), set to bounceBackrn[BoundaryConditionInstantiator2D] Warning: Could not addSlipBoundary (2, 0), discreteNormal=(0,0,0), set to bounceBackrn[BoundaryConditionInstantiator2D] Warning: Could not addSlipBoundary (2, 118), discreteNormal=(0,0,0), set to bounceBackrn[BoundaryConditionInstantiator2D] Warning: Could not addSlipBoundary (2, 0), discreteNormal=(0,0,0), set to bounceBackrn[BoundaryConditionInstantiator2D] Warning: Could not addSlipBoundary (2, 118), discreteNormal=(0,0,0), set to bounceBackrn[BoundaryConditionInstantiator2D] Warning: Could not addSlipBoundary (2, 0), discreteNormal=(0,0,0), set to bounceBackrn[BoundaryConditionInstantiator2D] Warning: Could not addSlipBoundary (2, 118), discreteNormal=(0,0,0), set to bounceBackrnrnThese are just a part of the command tips.rnDo you know why?rnrnYour sincerely, Benxi.

[robin.trunk]

Hi,rnrnI think this could be the same problem discussed in the topic “”Question about Cavity2d Example”” recently started by frankgao. Probably the points where the boundary can’t be set happen to be on the overlap?rnrnBest regardsrnRobin

[Benxi]

Quote:

Quote from robin.trunk on May 23, 2016, 08:39rnHi,rnrnI think this could be the same problem discussed in the topic “”Question about Cavity2d Example”” recently started by frankgao. Probably the points where the boundary can’t be set happen to be on the overlap?rnrnBest regardsrnRobin

rnrnrnThank you! I will go for a watch.

[Benxi]

Quote:

Quote from robin.trunk on May 23, 2016, 08:39rnHi,rnrnI think this could be the same problem discussed in the topic “”Question about Cavity2d Example”” recently started by frankgao. Probably the points where the boundary can’t be set happen to be on the overlap?rnrnBest regardsrnRobin

rnrnrnThank you! I will go for a watch.

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