tut3d_05

TUTORIAL 5: flow around a MOVING cylinder with MOVING local refinement

Goals of this Unit:

Movement of Walls and associated movement of local refinement

The fluid-mechanical problem Again the fluid mechanical setting remains the same as in the two previous examples. The only difference will be the movement of the cylinder in the center of the channel. Here should be a picture

Figure 15: Moving Cylinder perturbing the Fluid Flow

The main tool to move walls, bodies and other geometry elements such as points for smoothing length definitions is the MOVE flag to be given in the alias definition. If we want to move the cylinder in vertical direction, we include the following MOVE statement:

MOVE($MOVE_circle$) = ( %MOVE_velocity%, 0.0, 0.3, 0)

Instead if we want to move the cylinder in the x-y-plane with the velocity 0.9 in each direction (x and y) then we may use the MOVE statement in the following way

MOVE($MOVE_circle$) = ( %MOVE_velocity%, 0.9, 0.9, 0)

In order to associate the movement with a geometrical entity we have to modify the alias-section, i.e. assign the boundary elements concerned with the appropriate MOVE-flag:

"cylinder" = " BC$wallCyl$ ACTIVE$init_always$ IDENT%IDENT_slip% MAT$MatUSER$ TOUCH%TOUCH_geometrical% MOVE$MOVE_circle$ LAYER0 CHAMBER1 SYMMETRYFACE2 "

The higher particle density around the cylinder now will have to move in time, as the cylinder also moves. Thus, we attach the MOVE-flag also to the point around which the smoothing length is defined:

"hPoint" = "SMOOTH_LENGTH$P_0$ ACTIVE$init_always$ MOVE$MOVE_circle$ CHAMBER1 "

In this example, the cylinder is not subdivided into different parts of the hull as different boundary elements like in earlier cases. But the cylindrical curved surface and the two bases on the side are considered separately. Suggestions to explore FPM :

move cylinder in x-y plane to see results

Note: In order to reproduce Figure 15, load the state file tut05_figure15.pvsm in ParaView and choose 'Search files under specified directory'. Then, select the correct data directory (MESHFREE results folder).