Surface Problems

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Author Message   Augusto (cdfx) Member Username: cdfx Post Number: 14 Registered: 04-2007 Posted on Wednesday, August 01, 2007 - 12:49 am:    Hi Mr. Nelson I canīt understand why FlexPDE is reporting a error of tangled surfaces. Follow the code Thanks Mr! TITLE 'Blocks' COORDINATES cartesian3 VARIABLES vx(1e-6) vy(1e-6) vz(1e-6) p SELECT { method controls } ngrid = 10 errlim = 0.001 stages = 1 regrid = off DEFINITIONS { parameter definitions } LIx = -1.0 LIy = -1.0 LSx = 2.0 LSy = 2.0 dens = 1.0 visc = 0.01 penalty = 100.0 Pin = 0.1875 INITIAL VALUES vx = 0 vy = 0 vz = 0 p = Pin EQUATIONS vx: div(grad(vx)) - dx(p)/visc = dens*(vx*dx(vx) + vy*dy(vx) + vz*dz(vx))/visc vy: div(grad(vy)) - dy(p)/visc = dens*(vx*dx(vy) + vy*dy(vy) + vz*dz(vy))/visc vz: div(grad(vz)) - dz(p)/visc = dens*(vx*dx(vz) + vy*dy(vz) + vz*dz(vz))/visc p: div(grad(p)) = penalty * (dx(vx)+dy(vy)+dz(vz)) ! CONSTRAINTS { Integral constraints } EXTRUSION Z = -1.0, -0.8, -0.2, 0.2, 0.8, 1.2, 1.8, 2.0 BOUNDARIES REGION 1 START(LIx, LIy) value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 LINE TO (LSx, LIy) natural(vx)=0 natural(vy)=0 natural(vz)=0 value(p)=-Pin LINE TO (LSx, LSy) value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 LINE TO (LIx, LSy) natural(vx)=0 natural(vy)=0 natural(vz)=0 value(p)=Pin LINE TO CLOSE REPEAT j = -1 by 1 to 1 REPEAT i = -1 by 1 to 1 LIMITED REGION 2 surface 1 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 2 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 3 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 4 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 5 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 6 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 7 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 8 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 LAYER 1 VOID LAYER 3 VOID LAYER 5 VOID LAYER 7 VOID START(0.0 + i, 0.0 + j) value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 LINE TO (0.4 + i, 0.0 + j) TO (0.4 + i, 0.4 + j) TO (0.0 + i, 0.4 + j) TO CLOSE START (0.6 + i, 0.0 + j) value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 LINE TO (1.0 + i, 0.0 + j) TO (1.0 + i, 0.4 + j) TO (0.6 + i, 0.4 + j) TO CLOSE START (0.6 + i, 0.6 + j) value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 LINE TO (1.0 + i, 0.6 + j) TO (1.0 + i, 1.0 + j) TO (0.6 + i, 1.0 + j) TO CLOSE START (0.0 + i, 0.6 + j) value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 LINE TO (0.4 + i, 0.6 + j) TO (0.4 + i, 1.0 + j) TO (0.0 + i, 1.0 + j) TO CLOSE LIMITED REGION 3 surface 2 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 3 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 4 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 5 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 6 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 surface 7 value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 LAYER 2 VOID LAYER 4 VOID LAYER 6 VOID START (0.2 + i, 0.2 + j) value(vx)=0 value(vy)=0 value(vz)=0 natural(p)=0 LINE TO (0.8 + i, 0.2 + j) TO (0.8 + i, 0.8 + j) TO (0.2 + i, 0.8 + j) TO CLOSE ENDREPEAT ENDREPEAT monitors GRID(x,y,z) VECTOR(vx,vy) zoom(0.0, 0.0, 1.0, 1.0) ON z = 0.5 CONTOUR(vx) zoom(0.0, 0.0, 1.0, 1.0) ON z = 0.5 vector(vx, vz) zoom(0.0, 0.0, 1.0, 1.0) ON y = 0.5 plots GRID(x,y,z) VECTOR(vx,vy) zoom(0.0, 0.0, 1.0, 1.0) ON z = 0.5 points = 70 export format "#1 #2" file "block2d.vec" TABLE(vx, vy, vz) zoom(0.0, 0.0, 0.0, 1.0, 1.0, 1.0) points = 70 format "#1 #2 #3" file "block3d.vec" VECTOR(vx,vy) zoom(0.0, 0.0, 1.0, 1.0) ON z = 0.5 CONTOUR(vx) zoom(0.0, 0.0, 1.0, 1.0) ON z = 0.5 vector(vx, vz) zoom(0.0, 0.0, 1.0, 1.0) ON y = 0.5 end   Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 923 Registered: 06-2003 Posted on Wednesday, August 01, 2007 - 02:11 pm:    There are two problems here, caused by a misunderstanding of how FlexPDE constructs 3D extrusion models. 1. If you start at a point in the (X,Y) projection plane and run a vertical line up through the figure, the line will encounter a sequence of materials. In any REGION, the sequence of materials thus encountered must be the same. That is, there must be as many REGIONS as there are different material patterns on the vertical lines. In your case, there are three different patterns: 1) the on-off pattern of the grid arms, 2) the off-on pattern of the square corners, and 3) the on-on pattern of the square centers. Each of these must be a separate region. 2. A REPEAT is a text expansion process. When your REPEATS are expanded, it will result in a sequence: Region 2 Region 3 Region 2 Region 3 ... etc. Each of these REGION statements will become a separate region tabulation internally, regardless of the label you have put on it. In any surface, regions declared later will hide any region declared earlier, if they overlap. In your case, region "3" will overlap and hide some instances of region "2". The reverse will also be true in other parts of the domain. You should put the REPEAT inside the REGION definitions, not outside. If you do that, you will get only one set of REGION 2 patches and one set of REGION 3 patches, instead of eighteen different REGIONs.