1## libCEED: Navier-Stokes Example 2 3This page provides a description of the Navier-Stokes example for the libCEED library, based on PETSc. 4 5HONEE, a more fully featured fluid dynamics solver, can be found on [GitLab](https://gitlab.com/phypid/honee). 6 7The Navier-Stokes problem solves the compressible Navier-Stokes equations in three dimensions using an explicit time integration. 8The state variables are mass density, momentum density, and energy density. 9 10The main Navier-Stokes solver for libCEED is defined in [`navierstokes.c`](navierstokes.c) with different problem definitions according to the application of interest. 11 12## Build instructions 13 14Build by using: 15 16`make` 17 18and run with: 19 20``` 21./navierstokes -ceed [ceed] -problem [problem type] -degree [degree] 22``` 23 24## Runtime options 25 26% inclusion-fluids-marker 27 28The Navier-Stokes mini-app is controlled via command-line options. 29The following options are common among all problem types: 30 31:::{list-table} Common Runtime Options 32:header-rows: 1 33 34* - Option 35 - Description 36 - Default value 37 38* - `-ceed` 39 - CEED resource specifier 40 - `/cpu/self/opt/blocked` 41 42* - `-test_type` 43 - Run in test mode and specify whether solution (`solver`) or turbulent statistics (`turb_spanstats`) output should be verified 44 - `none` 45 46* - `-compare_final_state_atol` 47 - Test absolute tolerance 48 - `1E-11` 49 50* - `-compare_final_state_filename` 51 - Test filename 52 - 53 54* - `-problem` 55 - Problem to solve (`advection`, `density_current`, `euler_vortex`, `shocktube`, `blasius`, `channel`, `gaussian_wave`, and `taylor_green`) 56 - `density_current` 57 58* - `-implicit` 59 - Use implicit time integrator formulation 60 - 61 62* - `-degree` 63 - Polynomial degree of tensor product basis (must be >= 1) 64 - `1` 65 66* - `-q_extra` 67 - Number of extra quadrature points 68 - `0` 69 70* - `-ts_monitor_solution` 71 - PETSc output format, such as `cgns:output-%d.cgns` (requires PETSc `--download-cgns`) 72 - 73 74* - `-ts_monitor_solution_interval` 75 - Number of time steps between visualization output frames. 76 - `1` 77 78* - `-viewer_cgns_batch_size` 79 - Number of frames written per CGNS file if the CGNS file name includes a format specifier (`%d`). 80 - `20` 81 82* - `-checkpoint_interval` 83 - Number of steps between writing binary checkpoints. `0` has no output, `-1` outputs final state only 84 - `10` 85 86* - `-checkpoint_vtk` 87 - Checkpoints include VTK (`*.vtu`) files for visualization. Consider `-ts_monitor_solution`instead. 88 - `false` 89 90* - `-viz_refine` 91 - Use regular refinement for VTK visualization 92 - `0` 93 94* - `-output_dir` 95 - Output directory for binary checkpoints and VTK files (if enabled). 96 - `.` 97 98* - `-output_add_stepnum2bin` 99 - Whether to add step numbers to output binary files 100 - `false` 101 102* - `-continue` 103 - Continue from previous solution (input is step number of previous solution) 104 - `0` 105 106* - `-continue_filename` 107 - Path to solution binary file from which to continue from 108 - `[output_dir]/ns-solution.bin` 109 110* - `-continue_time_filename` 111 - Path to time stamp binary file (only for legacy checkpoints) 112 - `[output_dir]/ns-time.bin` 113 114* - `-bc_wall` 115 - Use wall boundary conditions on this list of faces 116 - 117 118* - `-wall_comps` 119 - An array of constrained component numbers for wall BCs 120 - 121 122* - `-bc_slip` 123 - Use weak slip boundary condition on this list of faces 124 - 125 126* - `-bc_symmetry_x` 127 - Use symmetry boundary conditions, for the x component, on this list of faces 128 - 129 130* - `-bc_symmetry_y` 131 - Use symmetry boundary conditions, for the y component, on this list of faces 132 - 133 134* - `-bc_symmetry_z` 135 - Use symmetry boundary conditions, for the z component, on this list of faces 136 - 137 138* - `-bc_inflow` 139 - Use inflow boundary conditions on this list of faces 140 - 141 142* - `-bc_outflow` 143 - Use outflow boundary conditions on this list of faces 144 - 145 146* - `-bc_freestream` 147 - Use freestream boundary conditions on this list of faces 148 - 149 150* - `-ts_monitor_turbulence_spanstats_collect_interval` 151 - Number of timesteps between statistics collection 152 - `1` 153 154* - `-ts_monitor_turbulence_spanstats_viewer` 155 - Sets the PetscViewer for the statistics file writing, such as `cgns:output-%d.cgns` (requires PETSc `--download-cgns`). Also turns the statistics collection on. 156 - 157 158* - `-ts_monitor_turbulence_spanstats_viewer_interval` 159 - Number of timesteps between statistics file writing (`-1` means only at end of run) 160 - `-1` 161 162* - `-ts_monitor_turbulence_spanstats_viewer_cgns_batch_size` 163 - Number of frames written per CGNS file if the CGNS file name includes a format specifier (`%d`). 164 - `20` 165 166* - `-ts_monitor_wall_force` 167 - Viewer for the force on each no-slip wall, e.g., `ascii:force.csv:ascii_csv` to write a CSV file. 168 - 169 170* - `-mesh_transform` 171 - Transform the mesh, usually for an initial box mesh. 172 - `none` 173 174* - `-snes_view` 175 - View PETSc `SNES` nonlinear solver configuration 176 - 177 178* - `-log_view` 179 - View PETSc performance log 180 - 181 182* - `-help` 183 - View comprehensive information about run-time options 184 - 185::: 186 187For the case of a square/cubic mesh, the list of face indices to be used with `-bc_wall`, `bc_inflow`, `bc_outflow`, `bc_freestream` and/or `-bc_symmetry_x`, `-bc_symmetry_y`, and `-bc_symmetry_z` are: 188 189:::{list-table} 2D Face ID Labels 190:header-rows: 1 191* - PETSc Face Name 192 - Cartesian direction 193 - Face ID 194 195* - faceMarkerBottom 196 - -z 197 - 1 198 199* - faceMarkerRight 200 - +x 201 - 2 202 203* - faceMarkerTop 204 - +z 205 - 3 206 207* - faceMarkerLeft 208 - -x 209 - 4 210::: 211 212:::{list-table} 3D Face ID Labels 213:header-rows: 1 214* - PETSc Face Name 215 - Cartesian direction 216 - Face ID 217 218* - faceMarkerBottom 219 - -z 220 - 1 221 222* - faceMarkerTop 223 - +z 224 - 2 225 226* - faceMarkerFront 227 - -y 228 - 3 229 230* - faceMarkerBack 231 - +y 232 - 4 233 234* - faceMarkerRight 235 - +x 236 - 5 237 238* - faceMarkerLeft 239 - -x 240 - 6 241::: 242 243### Boundary conditions 244 245Boundary conditions for compressible viscous flows are notoriously tricky. 246Here we offer some recommendations. 247 248#### Inflow 249 250If in a region where the flow velocity is known (e.g., away from viscous walls), use `bc_freestream`, which solves a Riemann problem and can handle inflow and outflow (simultaneously and dynamically). 251It is stable and the least reflective boundary condition for acoustics. 252 253If near a viscous wall, you may want a specified inflow profile. 254Use `bc_inflow` and see {ref}`example-blasius` and discussion of synthetic turbulence generation for ways to analytically generate developed inflow profiles. 255These conditions may be either weak or strong, with the latter specifying velocity and temperature as essential boundary conditions and evaluating a boundary integral for the mass flux. 256The strong approach gives sharper resolution of velocity structures. 257We have described the primitive variable formulation here; the conservative variants are similar, but not equivalent. 258 259#### Outflow 260 261If you know the complete exterior state, `bc_freestream` is the least reflective boundary condition, but is disruptive to viscous flow structures. 262If thermal anomalies must exit the domain, the Riemann solver must resolve the contact wave to avoid reflections. 263The default Riemann solver, HLLC, is sufficient in this regard while the simpler HLL converts thermal structures exiting the domain into grid-scale reflecting acoustics. 264 265If acoustic reflections are not a concern and/or the flow is impacted by walls or interior structures that you wish to resolve to near the boundary, choose `bc_outflow`. This condition (with default `outflow_type: riemann`) is stable for both inflow and outflow, so can be used in areas that have recirculation and lateral boundaries in which the flow fluctuates. 266 267The simpler `bc_outflow` variant, `outflow_type: pressure`, requires that the flow be a strict outflow (or the problem becomes ill-posed and the solver will diverge). 268In our experience, `riemann` is slightly less reflective but produces similar flows in cases of strict outflow. 269The `pressure` variant is retained to facilitate comparison with other codes, such as PHASTA-C, but we recommend `riemann` for general use. 270 271#### Periodicity 272 273PETSc provides two ways to specify periodicity: 274 2751. Topological periodicity, in which the donor and receiver dofs are the same, obtained using: 276 277```yaml 278dm_plex: 279 shape: box 280 box_faces: 10,12,4 281 box_bd: none,none,periodic 282``` 283 284The coordinates for such cases are stored as a new field with special cell-based indexing to enable wrapping through the boundary. 285This choice of coordinates prevents evaluating boundary integrals that cross the periodicity, such as for the outflow Riemann problem in the presence of spanwise periodicity. 286 2872. Isoperiodicity, in which the donor and receiver dofs are distinct in local vectors. This is obtained using `zbox`, as in: 288 289```yaml 290dm_plex: 291 shape: zbox 292 box_faces: 10,12,4 293 box_bd: none,none,periodic 294``` 295 296Isoperiodicity enables standard boundary integrals, and is recommended for general use. 297At the time of this writing, it only supports one direction of periodicity. 298The `zbox` method uses [Z-ordering](https://en.wikipedia.org/wiki/Z-order_curve) to construct the mesh in parallel and provide an adequate initial partition, which makes it higher performance and avoids needing a partitioning package. 299 300### Advection 301 302For testing purposes, there is a reduced mode for pure advection, which holds density $\rho$ and momentum density $\rho \bm u$ constant while advecting "total energy density" $E$. 303The advection problems can be run in both 2D and 3D, based on the DM defined for the problem. 304The following additional command-line options are available: 305 306:::{list-table} Advection Runtime Options 307:header-rows: 1 308 309* - Option 310 - Description 311 - Default value 312 - Unit 313 314* - `-rc` 315 - Characteristic radius of thermal bubble 316 - `1000` 317 - `m` 318 319* - `-units_meter` 320 - 1 meter in scaled length units 321 - `1E-2` 322 - 323 324* - `-units_second` 325 - 1 second in scaled time units 326 - `1E-2` 327 - 328 329* - `-units_kilogram` 330 - 1 kilogram in scaled mass units 331 - `1E-6` 332 - 333 334* - `-strong_form` 335 - Strong (1) or weak/integrated by parts (0) residual 336 - `0` 337 - 338 339* - `-stab` 340 - Stabilization method (`none`, `su`, or `supg`) 341 - `none` 342 - 343 344* - `-stab_tau` 345 - Formulation for $\tau$ in stabilization (`ctau`, `advdiff_shakib`) 346 - `ctau` 347 - 348 349* - `-Ctau_t` 350 - Scaling factor on the temporal portion of the $\tau$ formulation 351 - 0. 352 - 353 354* - `-Ctau_a` 355 - Scaling factor on the advection portion of the $\tau$ formulation 356 - $P^2$ 357 - 358 359* - `-CtauS` 360 - Scale coefficient for stabilization tau (nondimensional) 361 - `0` 362 - 363 364* - `-wind_type` 365 - Wind type in Advection (`rotation` or `translation`) 366 - `rotation` 367 - 368 369* - `-wind_translation` 370 - Constant wind vector when `-wind_type translation` 371 - `1,0,0` 372 - 373 374* - `-diffusion_coeff` 375 - Diffusion coefficient 376 - `0` 377 - 378 379* - `-E_wind` 380 - Total energy of inflow wind when `-wind_type translation` 381 - `1E6` 382 - `J` 383 384* - `-advection_ic_type` 385 - Initial condition type, from `sphere`, `cylinder`, `cosine_hill`, and `skew` 386 - `sphere` 387 - 388 389* - `-bubble_continuity` 390 - Different shapes for `sphere` and `cylinder` initial conditions, from `smooth`, `back_sharp`, `thick`, or `cosine` 391 - `smooth` 392 - 393::: 394 395For 3D advection, an example of the `rotation` mode can be run with: 396 397``` 398./navierstokes -problem advection -dm_plex_box_faces 10,10,10 -dm_plex_dim 3 -dm_plex_box_lower 0,0,0 -dm_plex_box_upper 8000,8000,8000 -bc_wall 1,2,3,4,5,6 -wall_comps 4 -wind_type rotation -implicit -stab su 399``` 400 401and the `translation` mode with: 402 403``` 404./navierstokes -problem advection -dm_plex_box_faces 10,10,10 -dm_plex_dim 3 -dm_plex_box_lower 0,0,0 -dm_plex_box_upper 8000,8000,8000 -wind_type translation -wind_translation .5,-1,0 -bc_inflow 1,2,3,4,5,6 405``` 406 407For 2D advection, an example of the `rotation` mode can be run with: 408 409``` 410./navierstokes -problem advection -dm_plex_box_faces 20,20 -dm_plex_box_lower 0,0 -dm_plex_box_upper 1000,1000 -bc_wall 1,2,3,4 -wall_comps 4 -wind_type rotation -implicit -stab supg 411``` 412 413and the `translation` mode with: 414 415``` 416./navierstokes -problem advection -dm_plex_box_faces 20,20 -dm_plex_box_lower 0,0 -dm_plex_box_upper 1000,1000 -units_meter 1e-4 -wind_type translation -wind_translation 1,-.5 -bc_inflow 1,2,3,4 417``` 418Note the lengths in `-dm_plex_box_upper` are given in meters, and will be nondimensionalized according to `-units_meter`. 419 420### Inviscid Ideal Gas 421 422#### Isentropic Euler vortex 423 424For the Isentropic Vortex problem, the following additional command-line options are available: 425 426:::{list-table} Isentropic Vortex Runtime Options 427:header-rows: 1 428 429* - Option 430 - Description 431 - Default value 432 - Unit 433 434* - `-center` 435 - Location of vortex center 436 - `(lx,ly,lz)/2` 437 - `(m,m,m)` 438 439* - `-units_meter` 440 - 1 meter in scaled length units 441 - `1E-2` 442 - 443 444* - `-units_second` 445 - 1 second in scaled time units 446 - `1E-2` 447 - 448 449* - `-mean_velocity` 450 - Background velocity vector 451 - `(1,1,0)` 452 - 453 454* - `-vortex_strength` 455 - Strength of vortex < 10 456 - `5` 457 - 458 459* - `-c_tau` 460 - Stabilization constant 461 - `0.5` 462 - 463::: 464 465This problem can be run with: 466 467``` 468./navierstokes -problem euler_vortex -dm_plex_box_faces 20,20,1 -dm_plex_box_lower 0,0,0 -dm_plex_box_upper 1000,1000,50 -dm_plex_dim 3 -bc_inflow 4,6 -bc_outflow 3,5 -bc_symmetry_z 1,2 -mean_velocity .5,-.8,0. 469``` 470 471#### Sod shock tube 472 473For the Shock Tube problem, the following additional command-line options are available: 474 475:::{list-table} Shock Tube Runtime Options 476:header-rows: 1 477 478* - Option 479 - Description 480 - Default value 481 - Unit 482 483* - `-units_meter` 484 - 1 meter in scaled length units 485 - `1E-2` 486 - 487 488* - `-units_second` 489 - 1 second in scaled time units 490 - `1E-2` 491 - 492 493* - `-yzb` 494 - Use YZB discontinuity capturing 495 - `none` 496 - 497 498* - `-stab` 499 - Stabilization method (`none`, `su`, or `supg`) 500 - `none` 501 - 502::: 503 504This problem can be run with: 505 506``` 507./navierstokes -problem shocktube -yzb -stab su -bc_symmetry_z 3,4 -bc_symmetry_y 1,2 -bc_wall 5,6 -dm_plex_dim 3 -dm_plex_box_lower 0,0,0 -dm_plex_box_upper 1000,100,100 -dm_plex_box_faces 200,1,1 -units_second 0.1 508``` 509 510### Newtonian viscosity, Ideal Gas 511 512For the Density Current, Channel, and Blasius problems, the following common command-line options are available: 513 514:::{list-table} Newtonian Ideal Gas problems Runtime Options 515:header-rows: 1 516 517* - Option 518 - Description 519 - Default value 520 - Unit 521 522* - `-units_meter` 523 - 1 meter in scaled length units 524 - `1` 525 - 526 527* - `-units_second` 528 - 1 second in scaled time units 529 - `1` 530 - 531 532* - `-units_kilogram` 533 - 1 kilogram in scaled mass units 534 - `1` 535 - 536 537* - `-units_Kelvin` 538 - 1 Kelvin in scaled temperature units 539 - `1` 540 - 541 542* - `-stab` 543 - Stabilization method (`none`, `su`, or `supg`) 544 - `none` 545 - 546 547* - `-c_tau` 548 - Stabilization constant, $c_\tau$ 549 - `0.5` 550 - 551 552* - `-Ctau_t` 553 - Stabilization time constant, $C_t$ 554 - `1.0` 555 - 556 557* - `-Ctau_v` 558 - Stabilization viscous constant, $C_v$ 559 - `36, 60, 128 for degree = 1, 2, 3` 560 - 561 562* - `-Ctau_C` 563 - Stabilization continuity constant, $C_c$ 564 - `1.0` 565 - 566 567* - `-Ctau_M` 568 - Stabilization momentum constant, $C_m$ 569 - `1.0` 570 - 571 572* - `-Ctau_E` 573 - Stabilization energy constant, $C_E$ 574 - `1.0` 575 - 576 577* - `-cv` 578 - Heat capacity at constant volume 579 - `717` 580 - `J/(kg K)` 581 582* - `-cp` 583 - Heat capacity at constant pressure 584 - `1004` 585 - `J/(kg K)` 586 587* - `-gravity` 588 - Gravitational acceleration vector 589 - `0,0,0` 590 - `m/s^2` 591 592* - `-lambda` 593 - Stokes hypothesis second viscosity coefficient 594 - `-2/3` 595 - 596 597* - `-mu` 598 - Shear dynamic viscosity coefficient 599 - `1.8e-5` 600 - `Pa s` 601 602* - `-k` 603 - Thermal conductivity 604 - `0.02638` 605 - `W/(m K)` 606 607* - `-newtonian_unit_tests` 608 - Developer option to test properties 609 - `false` 610 - boolean 611 612* - `-state_var` 613 - State variables to solve solution with. `conservative` ($\rho, \rho \bm{u}, \rho e$), `primitive` ($P, \bm{u}, T$), or `entropy` ($\frac{\gamma - s}{\gamma - 1} - \frac{\rho}{P} (e - c_v T),\ \frac{\rho}{P} \bm{u},\ -\frac{\rho}{P}$) where $s = \ln(P\rho^{-\gamma})$ 614 - `conservative` 615 - string 616 617* - `-idl_decay_time` 618 - Characteristic timescale of the pressure deviance decay. The timestep is good starting point 619 - `-1` (disabled) 620 - `s` 621 622* - `-idl_start` 623 - Start of IDL in the x direction 624 - `0` 625 - `m` 626 627* - `-idl_length` 628 - Length of IDL in the positive x direction 629 - `0` 630 - `m` 631 632* - `-idl_pressure` 633 - Pressure used for IDL reference pressure 634 - `-reference_pressure` 635 - `Pa` 636 637* - `-diff_filter_monitor` 638 - Enable differential filter TSMonitor 639 - `false` 640 - boolean 641 642* - `-diff_filter_grid_based_width` 643 - Use filter width based on the grid size 644 - `false` 645 - boolean 646 647* - `-diff_filter_width_scaling` 648 - Anisotropic scaling for filter width in wall-aligned coordinates (snz) 649 - `1,1,1` 650 - `m` 651 652* - `-diff_filter_kernel_scaling` 653 - Scaling to make differential kernel size equivalent to other filter kernels 654 - `0.1` 655 - `m^2` 656 657* - `-diff_filter_wall_damping_function` 658 - Damping function to use at the wall for anisotropic filtering (`none`, `van_driest`) 659 - `none` 660 - string 661 662* - `-diff_filter_wall_damping_constant` 663 - Constant for the wall-damping function. $A^+$ for `van_driest` damping function. 664 - 25 665 - 666 667* - `-diff_filter_friction_length` 668 - Friction length associated with the flow, $\delta_\nu$. Used in wall-damping functions 669 - 0 670 - `m` 671::: 672 673#### Gaussian Wave 674 675The Gaussian wave problem has the following command-line options in addition to the Newtonian Ideal Gas options: 676 677:::{list-table} Gaussian Wave Runtime Options 678:header-rows: 1 679 680* - Option 681 - Description 682 - Default value 683 - Unit 684 685* - `-freestream_riemann` 686 - Riemann solver for boundaries (HLL or HLLC) 687 - `hllc` 688 - 689 690* - `-freestream_velocity` 691 - Freestream velocity vector 692 - `0,0,0` 693 - `m/s` 694 695* - `-freestream_temperature` 696 - Freestream temperature 697 - `288` 698 - `K` 699 700* - `-freestream_pressure` 701 - Freestream pressure 702 - `1.01e5` 703 - `Pa` 704 705* - `-epicenter` 706 - Coordinates of center of perturbation 707 - `0,0,0` 708 - `m` 709 710* - `-amplitude` 711 - Amplitude of the perturbation 712 - `0.1` 713 - 714 715* - `-width` 716 - Width parameter of the perturbation 717 - `0.002` 718 - `m` 719 720::: 721 722This problem can be run with the `gaussianwave.yaml` file via: 723 724``` 725./navierstokes -options_file gaussianwave.yaml 726``` 727 728```{literalinclude} ../../../../../examples/fluids/gaussianwave.yaml 729:language: yaml 730``` 731 732#### Vortex Shedding - Flow past Cylinder 733 734The vortex shedding, flow past cylinder problem has the following command-line options in addition to the Newtonian Ideal Gas options: 735 736:::{list-table} Vortex Shedding Runtime Options 737:header-rows: 1 738 739* - Option 740 - Description 741 - Default value 742 - Unit 743 744* - `-freestream_velocity` 745 - Freestream velocity vector 746 - `0,0,0` 747 - `m/s` 748 749* - `-freestream_temperature` 750 - Freestream temperature 751 - `288` 752 - `K` 753 754* - `-freestream_pressure` 755 - Freestream pressure 756 - `1.01e5` 757 - `Pa` 758 759::: 760 761The initial condition is taken from `-reference_temperature` and `-reference_pressure`. 762To run this problem, first generate a mesh: 763 764```console 765$ make -C examples/fluids/meshes 766``` 767 768Then run by building the executable and running: 769 770```console 771$ make build/fluids-navierstokes 772$ mpiexec -n 6 build/fluids-navierstokes -options_file examples/fluids/vortexshedding.yaml -{ts,snes}_monitor_ 773``` 774 775The vortex shedding period is roughly 5.6 and this problem runs until time 100 (2000 time steps). 776The above run writes a file named `force.csv` (see `ts_monitor_wall_force` in `vortexshedding.yaml`), which can be postprocessed by running to create a figure showing lift and drag coefficients over time. 777 778```console 779$ python examples/fluids/postprocess/vortexshedding.py 780``` 781 782```{literalinclude} ../../../../../examples/fluids/vortexshedding.yaml 783:language: yaml 784``` 785 786#### Density current 787 788The Density Current problem has the following command-line options in addition to the Newtonian Ideal Gas options: 789 790:::{list-table} Density Current Runtime Options 791:header-rows: 1 792 793* - Option 794 - Description 795 - Default value 796 - Unit 797 798* - `-center` 799 - Location of bubble center 800 - `(lx,ly,lz)/2` 801 - `(m,m,m)` 802 803* - `-dc_axis` 804 - Axis of density current cylindrical anomaly, or `(0,0,0)` for spherically symmetric 805 - `(0,0,0)` 806 - 807 808* - `-rc` 809 - Characteristic radius of thermal bubble 810 - `1000` 811 - `m` 812 813* - `-theta0` 814 - Reference potential temperature 815 - `300` 816 - `K` 817 818* - `-thetaC` 819 - Perturbation of potential temperature 820 - `-15` 821 - `K` 822 823* - `-P0` 824 - Atmospheric pressure 825 - `1E5` 826 - `Pa` 827 828* - `-N` 829 - Brunt-Vaisala frequency 830 - `0.01` 831 - `1/s` 832::: 833 834This problem can be run with: 835 836``` 837./navierstokes -problem density_current -dm_plex_box_faces 16,1,8 -degree 1 -dm_plex_box_lower 0,0,0 -dm_plex_box_upper 2000,125,1000 -dm_plex_dim 3 -rc 400. -bc_wall 1,2,5,6 -wall_comps 1,2,3 -bc_symmetry_y 3,4 -mu 75 838``` 839 840#### Channel flow 841 842The Channel problem has the following command-line options in addition to the Newtonian Ideal Gas options: 843 844:::{list-table} Channel Runtime Options 845:header-rows: 1 846 847* - Option 848 - Description 849 - Default value 850 - Unit 851 852* - `-umax` 853 - Maximum/centerline velocity of the flow 854 - `10` 855 - `m/s` 856 857* - `-theta0` 858 - Reference potential temperature 859 - `300` 860 - `K` 861 862* - `-P0` 863 - Atmospheric pressure 864 - `1E5` 865 - `Pa` 866 867* - `-body_force_scale` 868 - Multiplier for body force (`-1` for flow reversal) 869 - 1 870 - 871::: 872 873This problem can be run with the `channel.yaml` file via: 874 875``` 876./navierstokes -options_file channel.yaml 877``` 878```{literalinclude} ../../../../../examples/fluids/channel.yaml 879:language: yaml 880``` 881 882(example-blasius)= 883 884#### Blasius boundary layer 885 886The Blasius problem has the following command-line options in addition to the Newtonian Ideal Gas options: 887 888:::{list-table} Blasius Runtime Options 889:header-rows: 1 890 891* - Option 892 - Description 893 - Default value 894 - Unit 895 896* - `-velocity_infinity` 897 - Freestream velocity 898 - `40` 899 - `m/s` 900 901* - `-temperature_infinity` 902 - Freestream temperature 903 - `288` 904 - `K` 905 906* - `-pressure_infinity` 907 - Atmospheric pressure, also sets IDL reference pressure 908 - `1.01E5` 909 - `Pa` 910 911* - `-temperature_wall` 912 - Wall temperature 913 - `288` 914 - `K` 915 916* - `-delta0` 917 - Boundary layer height at the inflow 918 - `4.2e-3` 919 - `m` 920 921* - `-platemesh_modify_mesh` 922 - Whether to modify the mesh using the given options below. 923 - `false` 924 - 925 926* - `-platemesh_refine_height` 927 - Height at which `-platemesh_Ndelta` number of elements should refined into 928 - `5.9E-4` 929 - `m` 930 931* - `-platemesh_Ndelta` 932 - Number of elements to keep below `-platemesh_refine_height` 933 - `45` 934 - 935 936* - `-platemesh_growth` 937 - Growth rate of the elements in the refinement region 938 - `1.08` 939 - 940 941* - `-platemesh_top_angle` 942 - Downward angle of the top face of the domain. This face serves as an outlet. 943 - `5` 944 - `degrees` 945 946* - `-platemesh_y_node_locs_path` 947 - Path to file with y node locations. If empty, will use mesh warping instead. 948 - `""` 949 - 950 951* - `-stg_use` 952 - Whether to use STG for the inflow conditions 953 - `false` 954 - 955 956* - `-n_chebyshev` 957 - Number of Chebyshev terms 958 - `20` 959 - 960 961* - `-chebyshev_` 962 - Prefix for Chebyshev snes solve 963 - 964 - 965 966::: 967 968This problem can be run with the `blasius.yaml` file via: 969 970``` 971./navierstokes -options_file blasius.yaml 972``` 973 974```{literalinclude} ../../../../../examples/fluids/blasius.yaml 975:language: yaml 976``` 977 978#### STG Inflow for Flat Plate 979 980Using the STG Inflow for the blasius problem adds the following command-line options: 981 982:::{list-table} Blasius Runtime Options 983:header-rows: 1 984 985* - Option 986 - Description 987 - Default value 988 - Unit 989 990* - `-stg_inflow_path` 991 - Path to the STGInflow file 992 - `./STGInflow.dat` 993 - 994 995* - `-stg_rand_path` 996 - Path to the STGRand file 997 - `./STGRand.dat` 998 - 999 1000* - `-stg_alpha` 1001 - Growth rate of the wavemodes 1002 - `1.01` 1003 - 1004 1005* - `-stg_u0` 1006 - Convective velocity, $U_0$ 1007 - `0.0` 1008 - `m/s` 1009 1010* - `-stg_mean_only` 1011 - Only impose the mean velocity (no fluctutations) 1012 - `false` 1013 - 1014 1015* - `-stg_strong` 1016 - Strongly enforce the STG inflow boundary condition 1017 - `false` 1018 - 1019 1020* - `-stg_fluctuating_IC` 1021 - "Extrude" the fluctuations through the domain as an initial condition 1022 - `false` 1023 - 1024 1025* - `-stg_dx` 1026 - Set the element size in the x direction. Default is calculated for box meshes, assuming equispaced elements. 1027 - 1028 - `m` 1029 1030* - `-stg_h_scale_factor` 1031 - Scale element size for cutoff frequency calculation 1032 - $1/p$ 1033 - 1034 1035::: 1036 1037This problem can be run with the `blasius.yaml` file via: 1038 1039``` 1040./navierstokes -options_file blasius.yaml -stg_use true 1041``` 1042 1043Note the added `-stg_use true` flag 1044This overrides the `stg: use: false` setting in the `blasius.yaml` file, enabling the use of the STG inflow. 1045