v2.4.2-LTS DoPhys Core Solver release notes: FP64 sparse AMG preconditioner & CUDA 12.4 support.
Deterministic PDE Solvers for Real-Time Hardware-in-the-Loop

Sub-millisecond physics kernels for engineering autonomy.

DoPhys Labs develops high-order finite-volume and symplectic integration engines compiled directly to multi-GPU and bare-metal targets. Designed for robotics state estimation, thermal-fluid digital twins, and inverse material design.

0.38 ms
$10^6$-DoF rigid-fluid step
$10^{-13}$
Symplectic energy drift / hr
Zero-Copy
DLPack / JAX / PyTorch IPC
import dophys as dp
from dophys.solvers import ImplicitFVM

# 1. Load unstructured hexahedral mesh (2.4M cells)
mesh = dp.Mesh.from_cgns("stator_cooling_v4.cgns", precision="fp64")

# 2. Configure coupled Navier-Stokes + Fourier heat conduction
solver = ImplicitFVM(
    mesh=mesh,
    preconditioner="amg_smoothed_aggregation",
    max_krylov_subspace=48,
    rtol=1e-9
)

# 3. Differentiable adjoint step for boundary optimization
state, grad = solver.step_with_adjoint(
    dt=2.5e-4,
    inlet_velocity=(14.2, 0.0, 0.0),
    heat_flux_w_m2=8.5e4
)
[INFO] AMG hierarchy built (5 levels, $\mathcal{C}_{\text{op}} = 1.34$) 18.2 ms
[ITER 06] $\|r_6\|_2 / \|b\|_2 = 4.18 \times 10^{-10}$ (converged) 1.41 ms
[ADJOINT] Reverse-mode sensitivity $\partial\mathcal{J}/\partial\alpha$ ready 0.94 ms
System Architecture

Built for strict conservation laws, not visual approximations.

Most fast simulators trade physical invariants for frame rate. DoPhys preserves discrete mass, momentum, and symplectic structure down to machine epsilon ($\epsilon_{\text{mach}} \approx 2.22 \times 10^{-16}$) while saturating modern memory bandwidth.

dophys::fem_fvm C++20 / CUDA

Matrix-Free High-Order Operators

Sum-factorized spectral element and finite-volume kernels that evaluate operators in $\mathcal{O}(p^{d+1})$ complexity without global sparse matrix assembly—achieving 78% of peak roofline memory bandwidth.

  • • Adaptive $hp$-multigrid & $\text{AoSoA-16}$ cache layout
  • • 2048-bit Kulisch deterministic reductions
  • • MPI + NVSHMEM multi-node halo exchange
dophys::autodiff Implicit Adjoints

Implicit Adjoint Differentiation

Instead of unrolling Krylov iterations on an AD tape, DoPhys solves the discrete adjoint system $[\partial\mathcal{R}/\partial u]^T \lambda = -(\partial\mathcal{J}/\partial u)^T$ via the implicit function theorem—cutting VRAM usage by $40\times$.

  • • Revolve binomial checkpointing for transient PDEs
  • • Direct custom_vjp bindings for JAX & PyTorch
  • • Matrix-free Hessian-vector products for Newton-CG
dophys::hil_rt PREEMPT_RT / C ABI

Deterministic Real-Time Runtime

Zero dynamic heap allocation after initialization. Designed for deployment inside $1\text{ kHz}$ control loops, aerospace hardware-in-the-loop benches, and $\mathrm{SE}(3)$ state-estimation filters.

  • • Bounded worst-case execution time ($\text{WCET} < 420\ \mu\text{s}$)
  • • Wait-free SPSC ring buffers for sensor fusion
  • • Standalone static library ($< 1.8\text{ MB}$ binary)
Interactive Solver Profile

Krylov-AMG Residual Convergence Inspector

Inspect real-world convergence trajectories $\|r_k\|_2 / \|r_0\|_2$ and memory roofline telemetry captured from DoPhys v2.4.2 across three representative multiphysics workloads.

Relative Residual $\|r_k\|_2 / \|r_0\|_2$ ($\log_{10}$ scale) Target $\epsilon_{\text{rtol}} = 10^{-9}$
10⁰ 10⁻³ 10⁻⁶ 10⁻⁹ 10⁻¹¹ DoPhys AMG-FGMRES Jacobi-PCG Baseline
Iter 0 Iter 2 Iter 4 Iter 6 Iter 8 Iter 10
Discretization Scheme WENO5-Z FVM + ESDIRK4
AMG Operator Complexity $\mathcal{C}_{\text{op}}$ 1.34 (5 V-Cycle Levels)
Sustained HBM/VRAM Bandwidth 748 GB/s (78.0% Roofline)
Primal + Adjoint Wall Time 29.8 ms + 18.5 ms
Reproducible Verification

Standard Validation Suite (v2.4.2)

Measured on single-socket AMD EPYC 9354 + NVIDIA RTX 6000 Ada (48GB ECC). Full input decks available in the documentation.

Precision: FP64 (IEEE 754) • Residual target: $\|r_k\|_2 / \|r_0\|_2 < 10^{-9}$
Problem / Mesh Degrees of Freedom ($N_{\text{DoF}}$) Legacy CPU (32-Core MPI) DoPhys v2.4 (Single GPU) Adjoint Backward Pass Speedup
3D Lid-Driven Cavity ($Re = 10,000$)
Hexahedral, $p=4$ sum-factorized spectral
$4.19 \times 10^6$ 612.0 ms / step 11.4 ms / step 6.8 ms $53.7\times$
Nonlinear Hyperelasticity (Neo-Hookean)
Quadratic tetrahedral arm, Newton-Krylov
$1.85 \times 10^6$ 284.5 ms / step 6.2 ms / step 3.1 ms $45.9\times$
Conjugate Heat Transfer (Cold Plate)
Coupled fluid-solid interface, AMG-PCG
$8.92 \times 10^6$ 1,490.0 ms / step 29.8 ms / step 18.5 ms $50.0\times$
Articulated $\mathrm{SE}(3)$ Multibody + Frictional Contact
Batched 64-environment RL rollout
$64 \times 148\text{ DoF}$ 19.4 ms / batch 0.31 ms / batch 0.22 ms $62.5\times$
Engineering Notes

Recent Technical Reports & Whitepapers

Deep dives into numerical stability, GPU kernel fusion, and mathematical proofs in our research archive.

View Full Monograph Archive →
TR-2025-04 • Oct 18, 2025

Eliminating Non-Associative Floating-Point Drift in Multi-GPU Krylov Solvers

How we implemented 2048-bit Kulisch fixed-point super-accumulators in shared memory to guarantee $\text{ULP}=0$ bit-identical convergence across MPI ranks.

H. Chen, M. Lindqvist Read Proofs & BibTeX →
TR-2025-03 • Aug 29, 2025

Preconditioned Implicit Adjoints for Stiff Thermo-Mechanical Contact

$C^2$-regularized contact barriers and block-triangular Schur complement preconditioners for inverse topology optimization.

A. Subramanian, K. Vance Read Proofs & BibTeX →
TR-2025-01 • May 12, 2025

Zero-Copy Surrogate Training: Bridging C++20 Field Tensors and JAX XLA

Designing custom XLA FFI calls that expose self-adjoint Leray-Helmholtz projection directly inside compiled neural operator pipelines.

H. Chen, R. Takahashi Read Proofs & BibTeX →
Licensing & Collaboration

Deploy DoPhys on your own cluster or test bench.

The core Python bindings and single-GPU academic license are free for non-commercial research. For multi-node enterprise deployments, source-code escrow, or custom boundary-condition engineering, contact our systems team.

OS Linux x86_64 & aarch64 ($\text{glibc} \ge 2.31$, Ubuntu 22.04+, RHEL 9)
GPU NVIDIA Compute Capability $\ge 8.0$ (Ampere, Ada, Hopper) & AMD ROCm 6.1
PGP Fingerprint: 4A9E 81C2 09F4 D11B 77E0 3C01 992B E84A D094 71C8