import pyopencl as cl mf = cl.mem_flags from string import Template import numpy import matplotlib.pyplot as plt import time kernel = """ float constant w[9] = { 1./36., 1./9., 1./36., 1./9. , 4./9., 1./9. , 1./36 , 1./9., 1./36. }; #define N_CELLS $nX*$nY unsigned int indexOfDirection(int i, int j) { return (i+1) + 3*(1-j); } unsigned int indexOfCell(int x, int y) { return y * $nX + x; } unsigned int idx(int x, int y, int i, int j) { return indexOfDirection(i,j)*N_CELLS + indexOfCell(x,y); } __global float f_i(__global __read_only float* f, int x, int y, int i, int j) { return f[idx(x,y,i,j)]; } float comp(int i, int j, float2 v) { return i*v.x + j*v.y; } float sq(float x) { return x*x; } float f_eq(float w, float d, float2 v, int i, int j, float dotv) { return w * d * (1.f + 3.f*comp(i,j,v) + 4.5f*sq(comp(i,j,v)) - 1.5f*dotv); } __kernel void collide_and_stream(__global __write_only float* f_a, __global __read_only float* f_b, __global __write_only float* moments, __global __read_only int* material) { const unsigned int gid = indexOfCell(get_global_id(0), get_global_id(1)); const uint2 cell = (uint2)(get_global_id(0), get_global_id(1)); const int m = material[gid]; if ( m == 0 ) { return; } float f0 = f_i(f_b, cell.x+1, cell.y-1, -1, 1); float f1 = f_i(f_b, cell.x , cell.y-1, 0, 1); float f2 = f_i(f_b, cell.x-1, cell.y-1, 1, 1); float f3 = f_i(f_b, cell.x+1, cell.y , -1, 0); float f4 = f_i(f_b, cell.x , cell.y , 0, 0); float f5 = f_i(f_b, cell.x-1, cell.y , 1, 0); float f6 = f_i(f_b, cell.x+1, cell.y+1, -1,-1); float f7 = f_i(f_b, cell.x , cell.y+1, 0,-1); float f8 = f_i(f_b, cell.x-1, cell.y+1, 1,-1); const float d = f0 + f1 + f2 + f3 + f4 + f5 + f6 + f7 + f8; float2 v = (float2)( (f5 - f3 + f2 - f6 + f8 - f0) / d, (f1 - f7 + f2 - f6 - f8 + f0) / d ); if ( m == 2 ) { v = (float2)(0.0f, 0.0f); } const float dotv = dot(v,v); f0 += $tau * (f_eq(w[0], d,v,-1, 1, dotv) - f0); f1 += $tau * (f_eq(w[1], d,v, 0, 1, dotv) - f1); f2 += $tau * (f_eq(w[2], d,v, 1, 1, dotv) - f2); f3 += $tau * (f_eq(w[3], d,v,-1, 0, dotv) - f3); f4 += $tau * (f_eq(w[4], d,v, 0, 0, dotv) - f4); f5 += $tau * (f_eq(w[5], d,v, 1, 0, dotv) - f5); f6 += $tau * (f_eq(w[6], d,v,-1,-1, dotv) - f6); f7 += $tau * (f_eq(w[7], d,v, 0,-1, dotv) - f7); f8 += $tau * (f_eq(w[8], d,v, 1,-1, dotv) - f8); f_a[0*N_CELLS + gid] = f0; f_a[1*N_CELLS + gid] = f1; f_a[2*N_CELLS + gid] = f2; f_a[3*N_CELLS + gid] = f3; f_a[4*N_CELLS + gid] = f4; f_a[5*N_CELLS + gid] = f5; f_a[6*N_CELLS + gid] = f6; f_a[7*N_CELLS + gid] = f7; f_a[8*N_CELLS + gid] = f8; moments[1*gid] = d; moments[2*gid] = v.x; moments[3*gid] = v.y; }""" class D2Q9_BGK_Lattice: def idx(self, x, y): return y * self.nX + x; def __init__(self, nX, nY): self.nX = nX self.nY = nY self.nCells = nX * nY self.tick = True self.platform = cl.get_platforms()[0] self.context = cl.Context(properties=[(cl.context_properties.PLATFORM, self.platform)]) self.queue = cl.CommandQueue(self.context) self.np_pop_a = numpy.ndarray(shape=(9, self.nCells), dtype=numpy.float32) self.np_pop_b = numpy.ndarray(shape=(9, self.nCells), dtype=numpy.float32) self.np_moments = numpy.ndarray(shape=(3, self.nCells), dtype=numpy.float32) self.np_material = numpy.ndarray(shape=(self.nCells, 1), dtype=numpy.int32) self.setup_geometry() self.equilibrilize() self.setup_anomaly() self.cl_pop_a = cl.Buffer(self.context, mf.READ_WRITE | mf.USE_HOST_PTR, hostbuf=self.np_pop_a) self.cl_pop_b = cl.Buffer(self.context, mf.READ_WRITE | mf.USE_HOST_PTR, hostbuf=self.np_pop_b) self.cl_material = cl.Buffer(self.context, mf.READ_ONLY | mf.USE_HOST_PTR, hostbuf=self.np_material) self.cl_moments = cl.Buffer(self.context, mf.READ_WRITE | mf.USE_HOST_PTR, hostbuf=self.np_moments) self.build_kernel() def setup_geometry(self): self.np_material[:] = 0 for x in range(1,self.nX-1): for y in range(1,self.nY-1): if x == 1 or y == 1 or x == self.nX-2 or y == self.nY-2: self.np_material[self.idx(x,y)] = 2 else: self.np_material[self.idx(x,y)] = 1 def equilibrilize(self): self.np_pop_a[(0,2,6,8),:] = 1./36. self.np_pop_a[(1,3,5,7),:] = 1./9. self.np_pop_a[4,:] = 4./9. self.np_pop_b[(0,2,6,8),:] = 1./36. self.np_pop_b[(1,3,5,7),:] = 1./9. self.np_pop_b[4,:] = 4./9. def setup_anomaly(self): bubbles = [ [ self.nX//4, self.nY//4], [ self.nX//4,self.nY-self.nY//4], [self.nX-self.nX//4, self.nY//4], [self.nX-self.nX//4,self.nY-self.nY//4] ] for x in range(0,self.nX-1): for y in range(0,self.nY-1): for [a,b] in bubbles: if numpy.sqrt((x-a)*(x-a)+(y-b)*(y-b)) < self.nX//10: self.np_pop_a[:,self.idx(x,y)] = 1./24. self.np_pop_b[:,self.idx(x,y)] = 1./24. def build_kernel(self): self.program = cl.Program(self.context, Template(kernel).substitute({ 'nX' : self.nX, 'nY' : self.nY, 'tau': "0.56f" })).build() #'-cl-single-precision-constant -cl-fast-relaxed-math') def evolve(self): if self.tick: self.tick = False self.program.collide_and_stream(self.queue, (self.nX,self.nY), (64,1), self.cl_pop_a, self.cl_pop_b, self.cl_moments, self.cl_material) else: self.tick = True self.program.collide_and_stream(self.queue, (self.nX,self.nY), (64,1), self.cl_pop_b, self.cl_pop_a, self.cl_moments, self.cl_material) def sync(self): self.queue.finish() def show(self, i): cl.enqueue_copy(LBM.queue, LBM.np_moments, LBM.cl_moments).wait(); density = numpy.ndarray(shape=(self.nX-2, self.nY-2)) for y in range(1,self.nY-1): for x in range(1,self.nX-1): density[x-1,y-1] = self.np_moments[0,self.idx(x,y)] plt.imshow(density, vmin=0.2, vmax=2.0, cmap=plt.get_cmap("seismic")) plt.savefig("result/density_" + str(i) + ".png") def MLUPS(cells, steps, time): return cells * steps / time * 1e-6 nUpdates = 1000 nStat = 100 print("Initializing simulation...\n") LBM = D2Q9_BGK_Lattice(1024, 1024) print("Starting simulation using %d cells...\n" % LBM.nCells) lastStat = time.time() for i in range(1,nUpdates+1): if i % nStat == 0: LBM.sync() #LBM.show(i) print("i = %4d; %3.0f MLUPS" % (i, MLUPS(LBM.nCells, nStat, time.time() - lastStat))) lastStat = time.time() LBM.evolve() #LBM.show(nUpdates)