rustytorch/crates/specialized/rtx-cfd/tests/overset_mms.rs

//! A-P2, step S4 (`docs/overset_metal_campaign.md` §5.9): the two-mesh
//! manufactured solution on the static overset.
//!
//! Unit square (closed box, exact Dirichlet velocity on every side, the
//! `mms_piso.rs` field and source, upwind) with the phantom circle at
//! (0.6, 0.45) r = 0.2 as the patch's inner wall (the exact velocity as its
//! Dirichlet), the skewed stretched annulus to r = 0.354 as the patch
//! (outer spacing = h), background n = 32 / 64 / 128. Gates: the
//! background's L2 on its fluid faces within 1.5× the embedded-circle
//! ladder (8.489e-3 / 4.341e-3 at n = 32 / 64) and first order to 128; the
//! patch's L2 on its interior cells ≤ 2× the background's at equal h and
//! first order; both divergence-free on their equation-carrying cells;
//! Schwarz rounds per corrector recorded; the overlap mass defect per step,
//! both sides, relative to the overlap flux scale — measured first.

mod overset_common;

use overset_common::{march, orders};
use rtx_cfd::CfdResult;

#[tokio::test]
async fn two_mesh_mms_recovers_the_single_mesh_levels_on_both_meshes() -> CfdResult<()> {
    let reference = [8.489e-3, 4.341e-3];
    let only: Option<usize> = std::env::var("RTX_OVERSET_N")
        .ok()
        .and_then(|v| v.parse().ok());
    let tol: f64 = std::env::var("RTX_OVERSET_SCHWARZ")
        .ok()
        .and_then(|v| v.parse().ok())
        .unwrap_or(1e-3);
    let mut bg = Vec::new();
    let mut patch = Vec::new();
    for (idx, n) in [32usize, 64, 128].into_iter().enumerate() {
        if only.is_some_and(|o| o != n) {
            continue;
        }
        let m = march(n, tol).await?;
        println!(
            "  overset n={n}: L2 background {:.6e} patch {:.6e} ({} steps); Schwarz rounds mean {:.2} max {} (failures {}); \
             worst bg residual {:.2e}, patch div {:.2e}; overlap mass defect (of the overlap flux) at steady state bg {:.3e} patch {:.3e}, worst over the transient bg {:.3e} patch {:.3e}",
            m.l2_background,
            m.l2_patch,
            m.steps,
            m.mean_rounds,
            m.max_rounds,
            m.schwarz_failures,
            m.worst_bg_residual,
            m.worst_patch_div_rel,
            m.final_defect_bg_rel,
            m.final_defect_patch_rel,
            m.worst_defect_bg_rel,
            m.worst_defect_patch_rel
        );
        println!(
            "    pressure: L2 (mean-shifted) background {:.3e} patch {:.3e}; level offset between the meshes {:+.3e}; largest fringe-vs-neighbours jump {:.3e} of the exact range",
            m.l2_p_background, m.l2_p_patch, m.p_offset_between_meshes, m.p_fringe_jump_rel
        );
        if let Some(r) = reference.get(idx) {
            assert!(
                m.l2_background < 1.5 * r,
                "n = {n}: background L2 {:.3e} > 1.5x embedded circle {r:.3e}",
                m.l2_background
            );
        }
        assert!(
            m.l2_patch < 2.0 * m.l2_background,
            "n = {n}: patch L2 {:.3e} > 2x background {:.3e}",
            m.l2_patch,
            m.l2_background
        );
        assert!(
            m.worst_patch_div_rel < 1e-9,
            "patch divergence {:.3e}",
            m.worst_patch_div_rel
        );
        bg.push(m.l2_background);
        patch.push(m.l2_patch);
    }
    if only.is_none() {
        let (ob, op) = (orders(&bg), orders(&patch));
        println!("  overset orders: background {ob:?}, patch {op:?}");
        assert!(
            ob.iter().all(|&x| (0.75..1.3).contains(&x)),
            "background orders {ob:?}"
        );
        assert!(
            op.iter().all(|&x| (0.7..1.6).contains(&x)),
            "patch orders {op:?}"
        );
    }
    Ok(())
}