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Added functions to compute force/torque on objects, added more benchmarks in Readme, added function to translate Mesh, added Stokes drag validation setup
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‎README.md

Lines changed: 10 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -138,6 +138,7 @@ Q = &Sigma;<sub><i>&alpha;&beta;</i></sub> <i>&Pi;<sub>&alpha;&beta;</sub></i><s
138138
- <kbd>V</kbd>: toggle stereoscopic rendering for VR
139139
- <kbd>B</kbd>: toggle VR-goggles/3D-TV mode for stereoscopic rendering
140140
- <kbd>N</kbd>/<kbd>M</kbd>: adjust eye distance for stereoscopic rendering
141+
- <kbd>H</kbd>: print current camera position/rotation in console as copy/paste command
141142
- <kbd>Esc</kbd>/<kbd>Alt</kbd>+<kbd>F4</kbd>: quit
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143144

@@ -181,13 +182,19 @@ In consequence, the arithmetic intensity of this implementation is 2.13 (FP32/FP
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| Nvidia Tesla K40m | 4.29 | 12 | 288 | 1131 (60%) | 1868 (50%) | 912 (24%) |
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| Nvidia Tesla K80 (1 GPU) | 4.11 | 12 | 240 | 916 (58%) | 1642 (53%) | 943 (30%) |
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| Nvidia Tesla K20c | 3.52 | 5 | 208 | 861 (63%) | 1507 (56%) | 720 (27%) |
185+
| AMD Radeon RX 6900 XT | 20.63 | 16 | 512 | 1968 (59%) | 4227 (64%) | 4207 (63%) |
186+
| AMD Radeon RX 5700 XT | 9.75 | 8 | 448 | 1368 (47%) | 3253 (56%) | 3049 (52%) |
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| AMD Radeon RX Vega 64 | 13.35 | 8 | 484 | 1875 (59%) | 2878 (46%) | 3227 (51%) |
188+
| AMD Radeon RX 580 4GB | 6.50 | 4 | 256 | 946 (57%) | 1848 (56%) | 1577 (47%) |
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| Nvidia GeForce RTX 3090 | 39.05 | 24 | 936 | 5418 (89%) | 10732 (88%) | 10215 (84%) |
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| Nvidia GeForce RTX 3080 10GB | 29.77 | 10 | 760 | 4230 (85%) | 8118 (82%) | 7714 (78%) |
191+
| Nvidia GeForce RTX 3060 | 13.17 | 12 | 360 | 2108 (90%) | 4070 (87%) | 3566 (76%) |
192+
| Nvidia GeForce RTX 3060M | 10.94 | 6 | 336 | 2019 (92%) | 4012 (92%) | 3572 (82%) |
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| Nvidia Quadro RTX 8000 Server | 14.93 | 48 | 624 | 2591 (64%) | 5408 (67%) | 5607 (69%) |
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| Nvidia GeForce RTX 2080 Ti | 13.45 | 11 | 616 | 3194 (79%) | 6700 (84%) | 6853 (86%) |
195+
| Nvidia GeForce RTX 2080 Super | 11.34 | 8 | 496 | 2434 (75%) | 5284 (82%) | 5087 (79%) |
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| Nvidia GeForce RTX 2060 Super | 7.18 | 8 | 448 | 2503 (85%) | 5035 (87%) | 4463 (77%) |
190-
| Nvidia Tesla T4 | 8.14 | 16 | 300 | 1356 (69%) | 2869 (74%) | 2887 (74%) |
197+
| Nvidia Tesla T4 | 8.14 | 15 | 300 | 1356 (69%) | 2869 (74%) | 2887 (74%) |
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| Nvidia GeForce GTX 1660 Ti | 5.48 | 6 | 288 | 1467 (78%) | 3041 (81%) | 3019 (81%) |
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| Nvidia Titan Xp | 12.15 | 12 | 548 | 2919 (82%) | 5495 (77%) | 5375 (76%) |
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| Nvidia GeForce GTX 1080 | 9.78 | 8 | 320 | 1623 (78%) | 3100 (75%) | 3182 (77%) |
@@ -200,7 +207,8 @@ In consequence, the arithmetic intensity of this implementation is 2.13 (FP32/FP
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| Nvidia Quadro K2000 | 0.73 | 2 | 64 | 312 (75%) | 444 (53%) | 171 (21%) |
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| Nvidia GeForce GT 630 (OEM) | 0.46 | 2 | 29 | 151 (81%) | 185 (50%) | 78 (21%) |
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| Apple M1 Pro GPU 16C 16GB | 4.10 | 11 | 200 | 1204 (92%) | 2329 (90%) | 1855 (71%) |
203-
| AMD Radeon Vega 8 Graphics | 1.23 | 7 | 38 | 157 (63%) | 282 (57%) | 288 (58%) |
210+
| AMD Radeon Vega 8 (4750G) | 2.15 | 27 | 57 | 263 (71%) | 511 (70%) | 501 (68%) |
211+
| AMD Radeon Vega 8 (3500U) | 1.23 | 7 | 38 | 157 (63%) | 282 (57%) | 288 (58%) |
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| Intel UHD Graphics 630 | 0.46 | 7 | 51 | 151 (45%) | 301 (45%) | 187 (28%) |
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| Intel HD Graphics 5500 | 0.35 | 3 | 26 | 75 (45%) | 192 (58%) | 108 (32%) |
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| Intel HD Graphics 4600 | 0.38 | 2 | 26 | 105 (63%) | 115 (35%) | 34 (10%) |

‎src/kernel.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1958,7 +1958,7 @@ string opencl_c_container() { return R( // ########################## begin of O
19581958
const float3 p5 = (float3)(p.x+0.5f, p.y-0.5f, p.z+0.5f); // +-+
19591959
const float3 p6 = (float3)(p.x+0.5f, p.y-0.5f, p.z-0.5f); // +--
19601960
const float3 p7 = (float3)(p.x-0.5f, p.y+0.5f, p.z+0.5f); // -++
1961-
if(!(not_xm||not_ym)) draw_line(p0, p2, c, camera_cache, bitmap, zbuffer); // to draw the entire surface, replace && by ||
1961+
if(!(not_xm||not_ym)) draw_line(p0, p2, c, camera_cache, bitmap, zbuffer); // to draw the entire surface, replace || by &&
19621962
if(!(not_xm||not_zm)) draw_line(p0, p4, c, camera_cache, bitmap, zbuffer);
19631963
if(!(not_ym||not_zm)) draw_line(p0, p6, c, camera_cache, bitmap, zbuffer);
19641964
if(!(not_xp||not_yp)) draw_line(p1, p3, c, camera_cache, bitmap, zbuffer);

‎src/lbm.cpp

Lines changed: 41 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -81,7 +81,9 @@ void LBM::sanity_checks_constructor() { // sanity checks on grid resolution and
8181
#ifndef VOLUME_FORCE
8282
if(fx!=0.0f||fy!=0.0f||fz!=0.0f) print_error("Volume force is set in LBM constructor in main_setup(), but VOLUME_FORCE is not enabled. Uncomment \"#define VOLUME_FORCE\" in defines.hpp.");
8383
#else // VOLUME_FORCE
84+
#ifndef FORCE_FIELD
8485
if(fx==0.0f&&fy==0.0f&&fz==0.0f) print_warning("The VOLUME_FORCE extension is enabled but the volume force in LBM constructor is set to zero. You may disable the extension by commenting out \"#define VOLUME_FORCE\" in defines.hpp.");
86+
#endif // FORCE_FIELD
8587
#endif // VOLUME_FORCE
8688
#ifndef SURFACE
8789
if(sigma!=0.0f) print_error("Surface tension is set in LBM constructor in main_setup(), but SURFACE is not enabled. Uncomment \"#define SURFACE\" in defines.hpp.");
@@ -243,6 +245,44 @@ void LBM::reset() { // reset simulation (takes effect in following run() call)
243245
void LBM::calculate_force_on_boundaries() { // calculate forces from fluid on TYPE_S nodes
244246
kernel_calculate_force_on_boundaries.set_parameters(2u, t).run();
245247
}
248+
float3 LBM::calculate_force_on_object(const uchar flag_marker) { // add up force for all nodes flagged with flag_marker
249+
double3 force(0.0, 0.0, 0.0);
250+
for(uint n=0u; n<get_N(); n++) {
251+
if(flags[n]==flag_marker) {
252+
force.x += (double)F.x[n];
253+
force.y += (double)F.y[n];
254+
force.z += (double)F.z[n];
255+
}
256+
}
257+
return float3(force.x, force.y, force.z);
258+
}
259+
float3 LBM::calculate_torque_on_object(const uchar flag_marker) { // add up torque around center of mass for all nodes flagged with flag_marker
260+
double3 center_of_mass(0.0, 0.0, 0.0);
261+
uint counter = 0u;
262+
for(uint n=0u; n<get_N(); n++) {
263+
if(flags[n]==flag_marker) {
264+
const float3 p = position(n);
265+
center_of_mass.x += (double)p.x;
266+
center_of_mass.y += (double)p.y;
267+
center_of_mass.z += (double)p.z;
268+
counter++;
269+
}
270+
}
271+
return calculate_torque_on_object(float3(center_of_mass.x/(double)counter, center_of_mass.y/(double)counter, center_of_mass.z/(double)counter)+center(), flag_marker);
272+
}
273+
float3 LBM::calculate_torque_on_object(const float3& rotation_center, const uchar flag_marker) { // add up torque around specified rotation center for all nodes flagged with flag_marker
274+
double3 torque(0.0, 0.0, 0.0);
275+
const float3 rotation_center_in_box = rotation_center-center();
276+
for(uint n=0u; n<get_N(); n++) {
277+
if(flags[n]==flag_marker) {
278+
const float3 t = cross(position(n)-rotation_center_in_box, float3(F.x[n], F.y[n], F.z[n]));
279+
torque.x += (double)t.x;
280+
torque.y += (double)t.y;
281+
torque.z += (double)t.z;
282+
}
283+
}
284+
return float3(torque.x, torque.y, torque.z);
285+
}
246286
#endif // FORCE_FIELD
247287

248288
#ifdef MOVING_BOUNDARIES
@@ -417,7 +457,7 @@ string LBM::device_defines() const { return
417457
"\n #define def_Nx "+to_string(Nx)+"u"
418458
"\n #define def_Ny "+to_string(Ny)+"u"
419459
"\n #define def_Nz "+to_string(Nz)+"u"
420-
"\n #define def_N " +to_string(get_N())+"ul"
460+
"\n #define def_N "+to_string(get_N())+"ul"
421461

422462
"\n #define D"+to_string(dimensions)+"Q"+to_string(velocity_set)+"" // D2Q9/D3Q15/D3Q19/D3Q27
423463
"\n #define def_velocity_set "+to_string(velocity_set)+"u" // LBM velocity set (D2Q9/D3Q15/D3Q19/D3Q27)

‎src/lbm.hpp

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -151,6 +151,9 @@ class LBM {
151151

152152
#ifdef FORCE_FIELD
153153
void calculate_force_on_boundaries(); // calculate forces from fluid on TYPE_S nodes
154+
float3 calculate_force_on_object(const uchar flag_marker=TYPE_S); // add up force for all nodes flagged with flag_marker
155+
float3 calculate_torque_on_object(const uchar flag_marker=TYPE_S); // add up torque around center of mass for all nodes flagged with flag_marker
156+
float3 calculate_torque_on_object(const float3& rotation_center, const uchar flag_marker=TYPE_S); // add up torque around specified rotation_center for all nodes flagged with flag_marker
154157
#endif // FORCE_FIELD
155158

156159
#ifdef MOVING_BOUNDARIES

‎src/setup.cpp

Lines changed: 46 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -114,6 +114,52 @@
114114

115115

116116

117+
/*void main_setup() { // Stokes drag validation
118+
const uint T = 100; // check error every T steps
119+
const float R = 32.0f; // sphere radius
120+
const float Re = 0.01f; // Reynolds number
121+
const float nu = 1.0f; // kinematic shear viscosity
122+
const float rho = 1.0f; // density
123+
const uint L = to_uint(8.0f*R); // simulation box size
124+
const float u = units.u_from_Re(Re, 2.0f*R, nu); // velocity
125+
// ######################################################### define simulation box size, viscosity and volume force ############################################################################
126+
LBM lbm(L, L, L, nu); // flow driven by equilibrium boundaries
127+
// #############################################################################################################################################################################################
128+
const uint N=lbm.get_N(), Nx=lbm.get_Nx(), Ny=lbm.get_Ny(), Nz=lbm.get_Nz(); for(uint n=0u, x=0u, y=0u, z=0u; n<N; n++, lbm.coordinates(n, x, y, z)) {
129+
// ########################################################################### define geometry #############################################################################################
130+
if(x==0u||x==Nx-1u||y==0u||y==Ny-1u||z==0u||z==Nz-1u) lbm.flags[n] = TYPE_E;
131+
if(sphere(x, y, z, lbm.center(), R)) {
132+
lbm.flags[n] = TYPE_S|TYPE_X; // flag boundary nodes for force summation additionally with TYPE_X
133+
} else {
134+
lbm.rho[n] = units.rho_Stokes(lbm.position(x, y, z), float3(-u, 0.0f, 0.0f), R, rho, nu);
135+
const float3 un = units.u_Stokes(lbm.position(x, y, z), float3(-u, 0.0f, 0.0f), R);
136+
lbm.u.x[n] = un.x;
137+
lbm.u.y[n] = un.y;
138+
lbm.u.z[n] = un.z;
139+
}
140+
} // #########################################################################################################################################################################################
141+
double E1=1000.0, E2=1000.0;
142+
while(true) {
143+
lbm.run(T);
144+
lbm.calculate_force_on_boundaries();
145+
lbm.F.read_from_device();
146+
const float3 force = lbm.calculate_force_on_object(TYPE_S|TYPE_X);
147+
const double F_theo = units.F_Stokes(rho, u, nu, R);
148+
const double F_sim = (double)length(force);
149+
const double E0 = fabs(F_sim-F_theo)/F_theo;
150+
print_info(to_string(lbm.get_t())+", expected: "+to_string(F_theo, 6u)+", measured: "+to_string(F_sim, 6u)+", error = "+to_string((float)(100.0*E0), 1u)+"%");
151+
if(converged(E2, E1, E0, 1E-4)) { // stop when error has sufficiently converged
152+
print_info("Error converged after "+to_string(lbm.get_t())+" steps to "+to_string(100.0*E0, 1u)+"%");
153+
wait();
154+
break;
155+
}
156+
E2 = E1;
157+
E1 = E0;
158+
}
159+
} /**/
160+
161+
162+
117163
/*void main_setup() { // cylinder in rectangular duct
118164
// ######################################################### define simulation box size, viscosity and volume force ############################################################################
119165
const float Re = 25000.0f;

‎src/utilities.hpp

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -4182,6 +4182,16 @@ struct Mesh { // triangle mesh
41824182
}
41834183
find_bounds();
41844184
}
4185+
inline void translate(const float3& translation) {
4186+
for(uint i=0u; i<triangle_number; i++) {
4187+
p0[i] += translation;
4188+
p1[i] += translation;
4189+
p2[i] += translation;
4190+
}
4191+
center += translation;
4192+
pmin += translation;
4193+
pmax += translation;
4194+
}
41854195
inline void rotate(const float3x3& rotation) {
41864196
for(uint i=0u; i<triangle_number; i++) {
41874197
p0[i] = rotation*(p0[i]-center)+center;
@@ -4190,6 +4200,9 @@ struct Mesh { // triangle mesh
41904200
}
41914201
find_bounds();
41924202
}
4203+
inline const float3& get_center() const {
4204+
return center;
4205+
}
41934206
};
41944207
inline Mesh* read_stl(const string& path, const float3& box_size, const float3& center, const float3x3& rotation, const float size) { // read binary .stl file
41954208
const string filename = create_file_extension(path, ".stl");

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