From 4c3e58fa2788592941a3b825345c43a3aa5e26c2 Mon Sep 17 00:00:00 2001 From: Omar Sobh Date: Fri, 18 Sep 2026 09:41:43 -0500 Subject: [PATCH] =?UTF-8?q?embedded3:=20DFG=202D-1=20ladder=20test=20(peri?= =?UTF-8?q?odic-z=20slab=20on=20the=20device=20cut=20wall)=20=E2=80=94=20S?= =?UTF-8?q?2-5's=20premise=20check?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Co-Authored-By: Claude Fable 5.1 --- .../rtx-cfd/tests/embedded3_dfg_2d1.rs | 234 ++++++++++++++++++ 1 file changed, 234 insertions(+) create mode 100644 crates/specialized/rtx-cfd/tests/embedded3_dfg_2d1.rs diff --git a/crates/specialized/rtx-cfd/tests/embedded3_dfg_2d1.rs b/crates/specialized/rtx-cfd/tests/embedded3_dfg_2d1.rs new file mode 100644 index 0000000..7488239 --- /dev/null +++ b/crates/specialized/rtx-cfd/tests/embedded3_dfg_2d1.rs @@ -0,0 +1,234 @@ +//! S2-5 premise check: Schäfer–Turek DFG 2D-1 (Re 20, steady) on the +//! device cut-cell wall as a periodic-z slab of 4 cells — a cheap ladder +//! (ny 62 / 123 / 246, D/h 15 / 30 / 60) that shows whether the cut +//! wall's drag converges to the reference or to an offset. Channel +//! 2.2 × 0.41, cylinder D 0.1 at (0.2, 0.2), inflow 4 U_m y (H − y)/H² +//! with U_m 0.3 (Ū 0.2), ρ 1, ν 1e-3. Reference (Nabh / FEATFLOW): +//! c_D 5.57953523384, c_L 0.010618948146, Δp 0.11752016697. +//! +//! `RTX_E3_DFG_NY=62 RTX_CUDA_ARCH=sm_120 cargo test --release -p rtx-cfd --features cuda --test embedded3_dfg_2d1 -- --ignored --nocapture` +#![cfg(feature = "cuda")] + +use rtx_cfd::solvers::incompressible::ConvectionScheme; +use rtx_cfd::solvers::incompressible::embedded3::step::device::DeviceStep; +use rtx_cfd::solvers::incompressible::embedded3::{ + Body, Boundaries, Field, Fluid, Grid, Parameters, Side, Solver, WallScheme, write_vtk, +}; +use std::io::Write as _; + +const H: f64 = 0.41; +const L: f64 = 2.2; +const D: f64 = 0.1; +const CX: f64 = 0.2; +const CY: f64 = 0.2; +const U_M: f64 = 0.3; +const U_BAR: f64 = 2.0 / 3.0 * U_M; +const NZ: usize = 4; +const RHO: f64 = 1.0; +const NU: f64 = 1e-3; + +fn env_f(name: &str, default: f64) -> f64 { + std::env::var(name) + .ok() + .and_then(|v| v.parse().ok()) + .unwrap_or(default) +} + +fn inflow(y: f64, _z: f64) -> f64 { + 4.0 * U_M * y * (H - y) / (H * H) +} + +#[test] +#[ignore = "item 12: the DFG rung on the device (minutes at ny 62, hours at ny 123)"] +fn dfg_2d_1_on_the_device() { + let ny = env_f("RTX_E3_DFG_NY", 62.0) as usize; + let h = H / ny as f64; + let nx = (L / h).round() as usize; + let nz = NZ; + let lz = nz as f64 * h; + let t_end = env_f("RTX_E3_DFG_T", 10.0); + // Explicit stability: CFL 0.3 on U_m and half the viscous limit. + let dt = (0.3 * h / U_M).min(0.5 * h * h / (6.0 * NU)); + let mut solver = Solver::new( + Fluid { + density: RHO, + viscosity: RHO * NU, + reference_velocity: U_BAR, + reference_length: D, + }, + Parameters { + corrector_steps: 2, + tolerance: 1e-8, + convection_scheme: ConvectionScheme::TvdVanAlbada, + wall_scheme: WallScheme::CutCell, + boundaries: Boundaries { + x1: Side::PressureOutlet, + z0: Side::Periodic, + z1: Side::Periodic, + ..Boundaries::default() + }, + ..Parameters::default() + }, + ); + solver.set_boundary_velocity(|x, y, z, _t| { + if x <= 0.0 { + (inflow(y, z), 0.0, 0.0) + } else { + (0.0, 0.0, 0.0) + } + }); + // The cylinder extruded across the width, with samples for the + // traction route (S2-1). + solver.set_body(Body::extruded( + rtx_cfd::solvers::incompressible::EmbeddedBody::circle(CX, CY, 0.5 * D), + lz, + )); + let g = Grid::cubic(nx, ny, nz, h); + let mut field = Field::new(g); + // Start from the inflow profile everywhere (a faster approach to steady). + for k in 0..nz { + for j in 0..ny { + let u0 = inflow((j as f64 + 0.5) * h, (k as f64 + 0.5) * h); + for i in 0..=nx { + field.u[g.uface(k, j, i)] = u0; + } + } + } + solver.initialize(&mut field); + let mask_cells = solver.mask().map_or(0, |m| m.fluid_cells()); + println!( + " DFG 2D-1 ny {ny}: {nx}×{ny}×{nz} = {} cells ({mask_cells} fluid), h {h:.4e}, dt {dt:.3e}, t_end {t_end}", + g.cells() + ); + let mut device = DeviceStep::new(solver, g); + device.upload(&field); + let steps = (t_end / dt).ceil() as usize; + let coef = 2.0 / (RHO * U_BAR * U_BAR * D * lz); + let csv = std::env::var("RTX_E3_DFG_CSV").ok().map(|p| { + let mut f = std::fs::File::create(p).expect("csv"); + writeln!( + f, + "t,cd_wall,cl_wall,cd_cv,cl_cv,dp,residual,cg,cd_sampler,cl_sampler" + ) + .unwrap(); + f + }); + let mut csv = csv; + let sample_every = (steps / 100).max(1); + let start = std::time::Instant::now(); + let mut last: Option<(f64, f64, f64, f64, f64)> = None; + let mut last_sampler = (f64::NAN, f64::NAN); + let mut settled = false; + for step in 0..steps { + let r = device.advance(dt); + if (step + 1) % sample_every == 0 || step + 1 == steps { + device.download(&mut field); + let solver = &device.solver; + let mask = solver.mask().expect("mask"); + let body = solver.body().expect("body"); + let t = solver.time(); + let fw = mask + .cut_wall_force(body, &field, RHO * NU, t) + .expect("wall"); + let margin = 1.5 * D; + let ci = |x: f64| ((x / h).round() as usize).clamp(2, nx - 2); + let cj = |y: f64| ((y / h).round() as usize).clamp(2, ny - 2); + let bx = ( + ci(CX - margin), + ci(CX + margin), + cj(CY - 0.15), + cj(CY + 0.15), + 0, + nz, + ); + let fcv = + mask.control_volume_force_with_walls(&field, dt, RHO, RHO * NU, None, bx, false); + // The reconstructed wall route (two probes on the cut polygons). + let fr = mask + .cut_wall_force_reconstructed(body, &field, RHO * NU, t, None) + .expect("reconstructed"); + let fs = rtx_cfd::solvers::incompressible::embedded3::SurfaceForce { + f: fr, + samples: 0, + skipped: 0, + }; + let (cd_s, cl_s) = (coef * fs.f[0], coef * fs.f[1]); + let zc = 0.5 * lz; + let p_front = mask + .pressure_at(&field.p, CX - 0.5 * D, CY, zc) + .unwrap_or(f64::NAN); + let p_back = mask + .pressure_at(&field.p, CX + 0.5 * D, CY, zc) + .unwrap_or(f64::NAN); + let dp = p_front - p_back; + let (cd, cl, cd_cv, cl_cv) = (coef * fw[0], coef * fw[1], coef * fcv[0], coef * fcv[1]); + println!( + " t {t:8.4}: c_D {cd:.4} (CV {cd_cv:.4}, reconstructed {cd_s:.4} skipped {}) c_L {cl:.5} (CV {cl_cv:.5}, reconstructed {cl_s:.5}) Δp {dp:.4} residual {:.1e} CG {} [{:.0} s]", + fs.skipped, + r.final_residual, + r.poisson_iterations, + start.elapsed().as_secs_f64() + ); + if let Some(f) = csv.as_mut() { + writeln!( + f, + "{t:.5},{cd:.6},{cl:.6},{cd_cv:.6},{cl_cv:.6},{dp:.6},{:.3e},{},{cd_s:.6},{cl_s:.6}", + r.final_residual, r.poisson_iterations + ) + .unwrap(); + } + last_sampler = (cd_s, cl_s); + if let Some((pcd, pcl, _, _, pdp)) = last { + let rel = ((cd - pcd) / cd) + .abs() + .max(((dp - pdp) / dp).abs()) + .max((cl - pcl).abs() / 0.01); + if rel < 1e-4 && t > 2.0 { + settled = true; + } + } + last = Some((cd, cl, cd_cv, cl_cv, dp)); + if settled { + println!(" settled (relative change < 1e-4 between samples)"); + break; + } + } + } + device.download(&mut field); + let solver = &device.solver; + let mask = solver.mask().expect("mask"); + if let Ok(dir) = std::env::var("RTX_E3_DFG_VTK") { + let path = std::path::Path::new(&dir).join(format!("dfg_2d1_ny{ny}.vtk")); + write_vtk(&path, &field, Some(mask)).expect("vtk"); + println!(" instant written to {}", path.display()); + } + let (cd, cl, cd_cv, cl_cv, dp) = last.expect("samples"); + { + // S2-1 diagnosis: each wall route split into its pressure and shear parts. + let body = solver.body().expect("body"); + let (po, so) = mask + .cut_wall_force_parts(body, &field, RHO * NU, solver.time()) + .expect("parts"); + let (pr, sr) = mask + .cut_wall_force_reconstructed_parts(body, &field, RHO * NU, solver.time(), None) + .expect("parts"); + println!( + " SPLIT ny {ny}: operator c_D pressure {:.4} + shear {:.4}; reconstructed pressure {:.4} + shear {:.4}", + coef * po[0], + coef * so[0], + coef * pr[0], + coef * sr[0] + ); + } + println!( + " FINAL ny {ny}: c_D {cd:.4} (CV {cd_cv:.4}, routes {:.2e} apart; reconstructed {:.4}, {:.2e} from CV) c_L {cl:.5} (CV {cl_cv:.5}, reconstructed {:.5}) Δp {dp:.4} — reference c_D 5.5795, c_L 0.010619, Δp 0.11752; {:.0} s", + ((cd - cd_cv) / cd).abs(), + last_sampler.0, + ((last_sampler.0 - cd_cv) / cd_cv).abs(), + last_sampler.1, + start.elapsed().as_secs_f64() + ); + if let Some(t) = device.timers() { + println!(" timers: {t:?}"); + } +}