TetGen meshing is a software that can produce high-quality unstructured tetrahedral mesh. As an independent software invoked through the command line when he can build generating executable files, or embedded in other programs. It supports many input file formats, such as .poly, .smesh, .node file, I used uses a .poly file as input. tetgen using manual only gives an example of a cube .poly file, if you want to generate a cylinder, or .poly file multiple cylinder assemblies will be no reference to the examples, and had clothed yourself.
The main idea is that the cylinder is configured with a polygonal approximation circle, so the text of the python code are also suitable for generating a polygon mesh.
Generating a single cylinder:
#generate only one cylinder import os import sys import time import math def main(argv): cputime_start = time.clock() cylinder_r = float(argv[1]) #the radius of the cylinder cylinder_h = float(argv[2]) #the height of the cylinder print '=================================================' #print '* The box mesh generation *' print '-------------------------------------------------' print 'The radius of the cylinder is %0.3f' % cylinder_r print 'The height of the cylinder is %0.3f' % cylinder_h boxname = 'cylinder' + '-' + str(cylinder_r) + '-' + str(cylinder_h) + '.poly' boxf = open(boxname,'w') theta = math.pi/64 #use a polygon to approximat a circle nodenum = 256 nodenum_half = 128 #save the information of nodes node = [[0 for col in range(4)] for row in range(nodenum)] for i in range(0,nodenum): node[i] = [i+1,0,0,0] for i in range(0, nodenum_half): node[i][1:] = [cylinder_r * math.cos(i * theta), cylinder_r * math.sin(i * theta), 0] for i in range(nodenum_half, nodenum): node[i][1:] = [cylinder_r * math.cos(i * theta), cylinder_r * math.sin(i * theta), cylinder_h] #save the information of facets facenum = nodenum_half + 2 # sides & top facet & bottom facet faceAll = [[0 for col in range(6)] for row in range(facenum-2)] for i in range(0, facenum-3): faceAll[i] = [4, i+1, i+2, i+2+nodenum_half, i+1+nodenum_half, 4] faceAll[facenum-3] = [4, facenum-2, 1, nodenum_half + 1, nodenum, 4] face = [[0 for col in range(5)] for row in range(facenum-2)] faceMark = [[0 for col in range(3)] for row in range(facenum-2)] for i in range(0,facenum-2): face[i] = faceAll[i][0:5] faceMark[i] = [1,0,faceAll[i][-1]] meshsize = [0.1] # the size of mesh numVolumMark = 1 # one region SolventMark = 1 # the region mark is 1 region = [[0 for col in range(6)] for row in range(numVolumMark)] for i in range(0,len(region)): region[i] = [i+1,0,0,0,0,0] region[0][1] = (node[0][1] + node[nodenum_half/2+nodenum_half][1])/2 region[0][2] = (node[0][2] + node[nodenum_half/2+nodenum_half][2])/2 region[0][3] = (node[0][3] + node[nodenum_half/2+nodenum_half][3])/2 region[0][4] = SolventMark region[0][5] = meshsize[0] line = '# Part 1 - node list\n' boxf.write(line) line = '# node count, 3 dim , no attribute, no boundary marker\n' boxf.write(line) line = str(nodenum) + '\t' + '3' + '\t' + '0' + '\t' + '0' + '\n' boxf.write(line) for i in range(0, nodenum): line = str(node[i][0]) + '\t' + str(node[i][1]) + '\t' + str(node[i][2]) + '\t' + str(node[i][3]) + '\n' boxf.write(line) line = '# Part 2 - face list\n' boxf.write(line) line = str(facenum) + '\t' + '1' + '\n' boxf.write(line) line = '# facet count, boundary marker\n' boxf.write(line) # the boundary mark of the bottom facet is 1 line = str(1) + '\t' + str(0) + '\t' + str(1) + '\n'\ boxf.write(line) line = str(nodenum_half) + '\t' for i in range(0, nodenum_half): line += str(i+1) + '\t' line += '\n' boxf.write(line) # the boundary mark of sides is 4 for i in range(0,facenum-2): line = str(faceMark[i][0]) + '\t' + str(faceMark[i][1]) + '\t' + str(faceMark[i][2]) + '\n' boxf.write(line) line = str(face[i][0]) + '\t' + str(face[i][1]) + '\t' + str(face[i][2]) + '\t' + str(face[i][3]) + '\t' + str(face[i][4]) + '\n' boxf.write(line) # the boundary mark of the top facet is 2 line = str(1) + '\t''+ Str (0) +\t' + str(2) + '\n' boxf.write(line) line = str(nodenum_half) + '\t' for i in range(0, nodenum_half): line += str(i +1+nodenum_half) + '\t' line += '\n' boxf.write(line) line = '# Part 3 - hole list\n' boxf.write(line) line = '0' + '\n' boxf.write(line) line = '# Part 4 - region list\n' boxf.write(line) line = str(numVolumMark) + '\n' boxf.write(line) for i in range(0,len(region)): line = str(region[i][0]) + '\t' + str(region[i][1]) + '\t' + str(region[i][2]) + '\t' + \ str(region[i][3]) + '\t' + str(region[i][4]) + '\t' + str(region[i][5]) + '\n' boxf.write(line) boxf.close() boxmeshfile = 'cylinder_' + str(cylinder_r) + '_' + str(cylinder_h) + '-' + 'refined1'+ '.mesh' cmd = './tetgen -pq1.414a0.1 >' + boxname os.system(cmd) cputime_end = time.clock() cputime = cputime_end - cputime_start print 'The total CPU time is %0.3fs' % cputime print '=================================================' if __name__ == '__main__': main(sys.argv)
Generating a combination cylinder:
#generate three cylinders import os import sys import time import math def main(argv): cputime_start = time.clock() #cylinder_r < bulk_r cylinder_r = float(argv[1]) #the radius of the cylinder cylinder_h = float(argv[2]) #the height of the cylinder bulk_r = float(argv[3]) #the radius of the bulk region bulk_h = float(argv[4]) #the height of the bulk region hole_flag = int(argv[5]) # 1 - there is a hole between the bulk region and the cylinder print '=================================================' #print '* The box mesh generation *' print '-------------------------------------------------' print 'The radius of the cylinder is %0.3f' % cylinder_r print 'The height of the cylinder is %0.3f' % cylinder_h print 'The radius of the bulk region is %0.3f' % bulk_r print 'The height of the bulk region is %0.3f' %bulk_h boxname = 'cylinder' + '-' + str(cylinder_r) + '-' + str(cylinder_h) + '.poly' boxf = open(boxname,'w') theta = math.pi/64 #use a polygon to approximat a circle nodenum_part = 128 nodenum = nodenum_part * 2 * 3 nodenum_half = nodenum_part * 3 #save the information of nodes node = [[0 for col in range(4)] for row in range(nodenum)] for i in range(0,nodenum): node[i] = [i+1,0,0,0] for i in range(0, nodenum_part): node[i][1:] = [bulk_r * math.cos(i * theta), bulk_r * math.sin(i * theta), 0] for i in range(nodenum_part, nodenum_part * 2): node[i][1:] = [bulk_r * math.cos(i * theta), bulk_r * math.sin(i * theta), bulk_h] for i in range(nodenum_part * 2, nodenum_part * 3): node[i][1:] = [cylinder_r * math.cos(i * theta), cylinder_r * math.sin(i * theta), bulk_h] for i in range(nodenum_part * 3, nodenum_part * 4): node[i][1:] = [cylinder_r * math.cos(i * theta), cylinder_r * math.sin(i * theta), cylinder_h + bulk_h] for i in range(nodenum_part * 4, nodenum_part * 5): node[i][1:] = [bulk_r * math.cos(i * theta), bulk_r * math.sin(i * theta), cylinder_h + bulk_h] for i in range(nodenum_part * 5, nodenum_part * 6): node[i][1:] = [bulk_r * math.cos(i * theta), bulk_r * math.sin(i * theta), cylinder_h + bulk_h + bulk_h] #save the information of facets if(hole_flag): facenum = nodenum_half + 4 # sides & top facet & bottom facet & interfaces between two regions else: facenum = nodenum_half + 6 faceAll = [[0 for col in range(6)] for row in range(nodenum_half)] # the boundary mark of sides of the bulk region is 3 for i in range(0, nodenum_part-1): faceAll[i] = [4, i+1, i+2, i+2+nodenum_part, i+1+nodenum_part, 3] faceAll[nodenum_part-1] = [4, nodenum_part, 1, nodenum_part + 1, nodenum_part * 2, 3] # the boundary mark of sides of the cylinder is 4 for i in range(nodenum_part, nodenum_part * 2-1): faceAll[i] = [4, i+1+nodenum_part, i+2+nodenum_part, i+2+2*nodenum_part, i+1+2*nodenum_part, 4] faceAll[nodenum_part*2-1] = [4, 3*nodenum_part, 2*nodenum_part+1, 3 * nodenum_part + 1, nodenum_part * 4, 4] # the boundary mark of sides of the bulk region is 3 for i in range(nodenum_part*2, nodenum_part * 3-1): faceAll[i] = [4, i+1+2*nodenum_part, i+2+2*nodenum_part, i+2+3*nodenum_part, i+1+3*nodenum_part, 3] faceAll[nodenum_part*3-1] = [4, 5*nodenum_part, 4*nodenum_part+1, 5 * nodenum_part + 1, nodenum_part * 6, 3] face = [[0 for col in range(5)] for row in range(nodenum_half)] faceMark = [[0 for col in range(3)] for row in range(nodenum_half)] for i in range(0,nodenum_half): face[i] = faceAll[i][0:5] faceMark[i] = [1,0,faceAll[i][-1]] meshsize = [10.0,1.0,10.0] # the size of mesh numVolumMark = 3 SolventMark = [1,1,1] # region marks of the three regions are all 1 region = [[0 for col in range(6)] for row in range(numVolumMark)] for i in range(0,len(region)): region[i] = [i+1,0,0,0,0,0] region[0][1] = (node[0][1] + node[nodenum_part/2+nodenum_part][1])/2 region[0][2] = (node[0][2] + node[nodenum_part/2+nodenum_part][2])/2 region[0][3] = (node[0][3] + node[nodenum_part/2+nodenum_part][3])/2 region[0][4] = SolventMark[0] region[0][5] = meshsize[0] region[1][1] = (node[2*nodenum_part][1] + node[nodenum_part/2+3*nodenum_part][1])/2 region[1][2] = (node[2*nodenum_part][2] + node[nodenum_part/2+3*nodenum_part][2])/2 region[1][3] = (node[2*nodenum_part][3] + node[nodenum_part/2+3*nodenum_part][3])/2 region[1][4] = SolventMark[1] region[1][5] = meshsize[1] region[2][1] = (node[4*nodenum_part][1] + node[nodenum_part/2+5*nodenum_part][1])/2 region[2][2] = (node[4*nodenum_part][2] + node[nodenum_part/2+5*nodenum_part][2])/2 region[2][3] = (node[4*nodenum_part][3] + node[nodenum_part/2+5*nodenum_part][3])/2 region[2][4] = SolventMark[2] region[2][5] = meshsize[2] line = '# Part 1 - node list\n' boxf.write(line) line = '# node count, 3 dim , no attribute, no boundary marker\n' boxf.write(line) line = str(nodenum) + '\t' + '3' + '\t' + '0' + '\t' + '0' + '\n' boxf.write(line) for i in range(0, nodenum): line = str(node[i][0]) + '\t' + str(node[i][1]) + '\t' + str(node[i][2]) + '\t' + str(node[i][3]) + '\n' boxf.write(line) line = '# Part 2 - face list\n' boxf.write(line) line = str(facenum) + '\t' + '1' + '\n' boxf.write(line) line = '# facet count, boundary marker\n' boxf.write(line) # the boundary mark of the bottom facet is 1 line = str(1) + '\t' + str(0) + '\t'+ Str (1) +'\n' boxf.write(line) line = str(nodenum_part) + '\t' for i in range(0, nodenum_part): line += str(i+1) + '\t' line += '\n' boxf.write(line) # the boundary mark of sides of the bulk region is 3 for i in range(0,nodenum_part): line = str(faceMark[i][0]) + '\t' + str(faceMark[i][1]) + '\t' + str(faceMark[i][2]) + '\n' boxf.write(line) line = str(face[i][0]) + '\t' + str(face[i][1]) + '\t' + str(face[i][2]) + '\t' + str(face[i][3]) + '\t' + str(face[i][4]) + '\n' boxf.write(line) # the boundary mark of the interface is 5 line = str(2) + '\t' + str(1) + '\t' + str(5) + '\n' boxf.write(line) line = str(nodenum_part) + '\t' for i in range(nodenum_part, 2*nodenum_part): line += str(i+1) + '\t' line +='\n' boxf.write(line) line = str(nodenum_part) + '\t' for i in range(2*nodenum_part, 3*nodenum_part): line += str(i+1) + '\t' line +='\n' boxf.write(line) line = str(1) + '\t' + str(0) + '\t' + str(0) + '\t' + str(bulk_h) + '\n' boxf.write(line) # the boundary mark of the facet on the hole is 6 if(hole_flag==0): line = str(1) + '\t' + str(0) + '\t' + str(6) + '\n' boxf.write(line) line = str(nodenum_part) + '\t' for i in range(2*nodenum_part, 3*nodenum_part): line += str(i+1) + '\t' line +='\n' boxf.write(line) # the boundary mark of sides of the cylinder is 4 for i in range(nodenum_part,2*nodenum_part): line = str(faceMark[i][0]) + '\t' + str(faceMark[i][1]) + '\t' + str(faceMark[i][2]) + '\n' boxf.write(line) line = str(face[i][0]) + '\t' + str(face[i][1]) + '\t' + str(face[i][2]) + '\t' + str(face[i][3]) + '\t' + str(face[i][4]) + '\n' boxf.write(line) # the boundary mark of the interface is 5 line = str(2) + '\t' + str(1) + '\t' + str(5) + '\n' boxf.write(line) line = str(nodenum_part) + '\t' for i in range(4*nodenum_part, 5*nodenum_part): line += str(i+1) + '\t' line +='\n' boxf.write(line) line = str(nodenum_part) + '\t' for i in range(3*nodenum_part, 4*nodenum_part): line += str(i+1) + '\t' line +='\n' boxf.write(line) line = str(1) + '\t' + str(0) + '\t' + str(0) + '\t' + str(bulk_h+cylinder_h) + '\n' boxf.write(line) # the boundary mark of the facet on the hole is 6 if(hole_flag==0): line = str(1) + '\t' + str(0) + '\t' + str(6) + '\n' boxf.write(line) line = str(nodenum_part) + '\t' for i in range(3*nodenum_part, 4*nodenum_part): line += str(i+1) + '\t' line +='\n' boxf.write(line) # the boundary mark of sides of the bulk region is 3 for i in range(2*nodenum_part,3*nodenum_part): line = str(faceMark[i][0]) + '\t' + str(faceMark[i][1]) + '\t' + str(faceMark[i][2]) + '\n' boxf.write(line) line = str(face[i][0]) + '\t' + str(face[i][1]) + '\t' + str(face[i][2]) + '\t' + str(face[i][3]) + '\t' + str(face[i][4]) + '\n' boxf.write(line) # the boundary mark of the top facet is 2 line = str(1) + '\t' + str(0) + '\t' + str(2) + '\n' boxf.write(line) line = str(nodenum_part) + '\t' for i in range(5*nodenum_part, 6*nodenum_part): line += str(i+1) + '\t' line +='\n' boxf.write(line) line = '# Part 3 - hole list\n' boxf.write(line) line = '0' + '\n' boxf.write(line) line = '# Part 4 - region list\n' boxf.write(line) line = str(numVolumMark) + '\n' boxf.write(line) for i in range(0,len(region)): line = str(region[i][0]) + '\t' + str(region[i][1]) + '\t' + str(region[i][2]) + '\t' + \ str(region[i][3]) + '\t' + str(region[i][4]) + '\t' + str(region[i][5]) + '\n' boxf.write(line) boxf.close() #boxmeshfile = 'box_analytic' + '-'+ str(boxWidth) + '-'+ str(boxLength) + '-' + str(boxHeight) + '-' + str(meshsize[0]) + '.mesh' boxmeshfile = 'cylinder_reservoir_' + str(cylinder_r) + '_' + str(cylinder_h) + '-' + 'refine'+ '.mesh' cmd = './tetgen2medit ' + boxname + ' ' + '-pq1.414a0.1 >' + boxmeshfile os.system(cmd) cputime_end = time.clock() cputime = cputime_end - cputime_start print 'The total CPU time is %0.3fs' % cputime print '=================================================' if __name__ == '__main__': main(sys.argv)
FIG intermediate the two cylindrical surfaces not vertical.
FIG no intermediate the two cylindrical surfaces, marked 6.
