New features/Highlights v24.09

New Network Architectures

• DLWP HEALPix coupled ocean model for predicting the coupled dynamics of Earth’s weather

• Graph Transformer processor for GraphCast

• Bistride Multiscale MeshGraphNet

Features and Enhancements

• Utility to reconstruct surfaces from SDF to compute physical quantities over arbitrary surfaces

• Modular physics informing utilities to infuse knowledge guided training into any pytorch training workflow

• Utilities to compute metrics such as surface and line integrals and CFD specific metrics for validating models against first principles

• Ability to extend data-driven models from Modulus Core with Physics from Modulus Sym with support for spatial gradients calculations using autodiff, finite difference, meshless finite difference, spectral and least squares methods

• Automatic Mixed Precision (AMP) for calculating derivatives

Recipes and Examples

• Improved CorrDiff training recipe to improve usability for other datasets

• Examples showcasing various uses of CSG and Tessellation (STL) geometries and Physics losses in pure physics and data + physics driven workflows

New features/Highlights v24.07

New Network Architectures

• A graph neural network model with temporal multi-head attention for transient physics, demonstrated on the vortex shedding example.

Features and Enhancements

• Warp based geometry utility for handling STL inputs.

• Generalized accelerated dataloader for VTK files.

• Mesh processing features supporting OBJ & VTP files.

Recipes and Examples

• Distributed GNN sample demonstrating distributed GNNs on single-level mesh, multi-level mesh and distributed I/O.

• GenAI sample demonstrating use of diffusion model for 2D turbulence super resolution.

• Recipe to benchmark and holistically validate a PyTorch model against first principles using turbulence and external aerodynamic flow use cases.

• Training recipes for weather models that include DLWP HEALPix, Pangu, Fengu and SwinRNN.

• Extended the external aerodynamic flow benchmark with DrivAerNet dataset.

New features/Highlights v24.04

Features and Enhancements

• ClimateDatapipe: an improved datapipe for HDF5/NetCDF4 formatted climate data.

• Warp neighbor search routine with minimal example.

• Performance optimizations to CorrDiff: Utilizing asynchronous I/O, torch.compile, AMP, and batched inference.

• Custom Group Norm implementation to be compatible with channels last memory format in Modulus’ SongUNet architecture.

Recipes and Examples

• Earth2Studio – set of workflows and utilities for scientists and researchers to explore and experiment with the use of AI models for weather and climate.

• Reservoir examples using GenAI and CCUS workflows.

• Physics-informed Nonlinear Shallow Water Equations example.

• Jupyter notebook validating a GNN model, trained on data, against physics - vortex shedding.

• Unified training recipe for global weather models. Supports, SFNO, AFNO, and GraphCast.

New features/Highlights v24.01

Feature Enhancements

• Distributed Utilities Improvements:

  • Upgrades to distributed utilites to facilitate novel model parallel strategies.

  • Configuration structure for models to describe their parallelization group structure.

  • DistributedManager utility to instantiate process groups based on a model’s process group config.

  • Helper functions to facilitate distributed training with shared parameters using gradient reduction hooks.

  • Improved usage of GraphPartition, with more flexible ways of defining a partitioned graph for distributed GNNs.

Recipes and Examples

• Generative Correction Diffusion Model (CorrDiff) for Km-scale Atmospheric Downscaling.

• Force prediction example for Molecular Dynamics using GNNs.

• Examples and recipes showcasing physics-informing data-driven workflows

  • Physics informed DeepONet and Physics informed Neural Operators

  • Physics informed fine-tuning of GNN predictions

• Example use case demonstrating use of FNOs for

  • Brain anomaly detection

  • Reservoir modeling

New features/Highlights v23.11

Modulus container is now supported on aarch64 architecture.

New Network Architectures

• Support for Diffusion model architectures that include DDPM++, NCSN++, and ADM.

Training Features

• Introducing diffusion modeling framework to explore and experiment with different diffusion models and sampling strategies.

• New distributed FFT utility and updates to DistributedManager utility to better handle process groups

New features/Highlights v23.09

This is a minor release with bug fixes and some minor updates

• Updated Model checkpointing (with new ‘.mdlus’ save type) saves models arguments and version allowing for easier deploment and version control

• Data download scripts to fetch ERA5 data from CDS api. This allows users to train models such as AFNO or Graphcast.

New features/Highlights v23.08

Training Features

• Added support for PyTorch 2.0

• Added support to CUDA 12.0

• Added support to Python 3.10

Recipes and Examples

• External Aerodynamics sample using GNNs to predict drag over an Ahmed body geometry

• Global weather prediction using DLWP model

New features/Highlights v23.05

New Network Architectures

• Support for GNNs starting with MeshGaphNet and GraphCast models.

• Support for Convolutional RNN-based models.

Training Features

• Modulus has been rearchitected into modules:

  • Modulus Core is the base module that consists of the core components of the framework for developing Physics-ML models

  • Modulus Sym provides an abstraction layer for using PDE-based symbolic loss functions

  • Modulus Launch provides optimized training recipes for data driven Physics-ML models

• Expanded feature set for AI weather and climate models applications

  • SOTA models including : FourCastNet and GraphCast

  • Climate and weather model skill evaluation metrics

  • Optimal training recipes with efficient ETL pipelines for loading weather datasets using NVIDIA DALI.

• Fast utilities and kernels for producing training data on-the-fly using NVIDIA’s Warp library.

• Cugraph-Ops (Nvidia’s GNN library of highly optimized and performant primitives) support for GraphCast that reduces the training time by 30% compared to DGL.

Recipes and Examples

• GraphCast for global weather prediction

• MeshGraphNet for parameterized vortex shedding

• 2D and 3D Convolutional RNNs for fluid flow and reaction-diffusion applications

• Darcy flow FNO example with NVIDIA Warp datapipe.

• Darcy flow Nested FNO training example in Modulus launch.

New features/Highlights v22.09

New Network Architectures

• Generalized Neural Operators: Extended Fourier Neural Operator (FNO) and DeepONet to support compatibility with other built in Modulus Sym networks. FNO can now use any point wise network inside of Modulus Sym for its decoder. DeepONet can now accept any branch/trunk net.

• Model parallelism has been introduced as a beta feature with model-parallel AFNO. This allows for parallelizing the model across multiple GPUs along the channel dimension.

• Support for the self-scalable tanh (Stan) activation function is now available.

Training features

• Criteria based training termination: APIs to terminate training based on the convergence criteria like total loss or individual loss terms.

• Utilities for Nondimensionalization: Nondimensionalization tools are now provided in Modulus Sym to help users properly scale their system’s units for physics informed training.

• Causal weighting scheme: Causal weighting scheme by reformulating the losses for the residual and initial conditions for better convergence in case of transient problems.

• Selective Equations Term Suppression: Allows creation of different instances of the same PDE and freeze different terms to improve convergence on stiff PDEs in physics informed training.

Performance Enhancements

• FuncTorch Integration: Modulus Sym now supports FuncTorch gradient calculations (A Jax like paradigm) for faster gradient calculations in physics-informed training.

Documentation Enhancements

• More example-guided workflows for beginners and Jupyter notebook based getting started example.

• Enhancements to Modulus Sym Features section to serve as a user guide.

New features/Highlights v22.07

New Network Architectures

• Generalized DeepONet architecture: DeepONet in Modulus Sym is restructured so that it can easily be applied to data-informed and physics-informed 1D/2D problems with any arbitrary network architectures as the backbone.

• FourCastNet: FourCastNet, short for Fourier ForeCasting Neural Network, is a global data-driven weather forecasting model that provides accurate short to medium range global predictions at \(0.25^{\circ}\) resolution. In the current iteration, FourCastNet forecasts 20 atmospheric variables. (Paper)

Training features

• L2-L1 Loss Decaying: A L2 to L1 loss decay is now supported. This feature allows users to slowly transition between a L2 loss and L1 loss during training. This can improve training accuracy since decaying to an L1 loss can help reduce the impact of outlier training points with unstable loss values. This can be particularly useful for problems with singularities and sharp gradient interfaces.

Performance Enhancements

• Meshless Finite Differentiation: Modulus Sym now includes a new approximate differentiation approach for physics-informed problems based on finite difference calculations. This new method allows for the computational complexity of training to be dramatically decrease compared to the standard automatic differentiation approach. For some examples this can yield upto 4x speed up in training time with minimal impact on accuracy. This feature is in beta and subject to change with improvements in the future.

• Dataset Refactor: Both map style PyTorch datasets and iterable style datasets are supported inside of Modulus Sym for both physics based and data-driven problems. This includes built in functionality for multithreading workers and data parallel training in multi-GPU / multi-node environments.

• Tiny CUDA NN: Modulus Sym now offers several Tiny CUDA NN architectures which are fully fused neural networks. These models provide a lightweight, heavily optimized implementation which can improve computation performance. Tiny Cuda NN combined with meshless finite derivatives can yield significant speed up over vanilla physics-informed implementations.

• CUDA Graphs: Modulus Sym now leverages CUDA graphs to record the series of CUDA kernels used during a training iteration and save it as a single graph that can then be replayed on the GPU as opposed to individual launches reducing CPU launch latency bottlenecks.

• Geometry Module Refactor: The geometry module inside of Modulus Sym has been refactored to improve point sampling performance for both continuous and tessellated geometries. This greatly reduces the initial overhead of creating training/testing datasets from complex geometries.

New features/Highlights v22.03

New Network Architectures

• Physics inspired Neural Network model that uses global convolutions in spectral space as an inductive bias for training Neural Network models of physical systems. It incorporates important spatial and temporal correlations, which strongly govern the dynamics of many physical systems that obey PDE laws.

• PINO is the explicitly physics-informed version of the FNO. PINO combines the operator learning and function optimization frameworks. In the operator learning phase, PINO learns the solution operator over multiple instances of the parametric PDE family.

• An adaptive FNO for scaling self-attention to high resolution images in vision transformers by establishing a link between operator learning and token mixing. AFNO is based on FNO which allows framing token mixing as a continuous global convolution without any dependence on the input resolution. The resulting model is highly parallel with a quasi-linear complexity and has linear memory in the sequence size.

• A DeepONet consists of two sub-networks, one for encoding the input function and another for encoding the locations and then merged to compute the output. Using inductive bias, DeepONets are shown to reduce the generalization error compared to the fully connected networks.

Modeling Enhancements

• Two equation turbulence: Solution to two equation turbulence (k-epsilon & k-omega) models on a fully developed turbulent flow in a 2D channel case using wall functions. Two types of wall functions (standard and Launder-Spalding) have been tested and demonstrated on the above example problem.

• Exact boundary condition imposition: A new algorithm based on the theory of R-functions and transfinite interpolation is implemented to exactly impose the Dirichlet boundary conditions on 2D geometries. In this algorithm, the neural network solution to a given PDE is constrained to a boundary condition aware and geometry aware ansatz, and a loss function based on the first-order formulation of the PDE is minimized to train a solution that exactly satisfies the boundary conditions.

Training features

• Support for new optimizers: Modulus Sym now supports 30+ optimizers including the built-in PyTorch optimizers and the optimizers in the torch-optimizer` library. Includes support for AdaHessian, a second-order stochastic optimizer that approximates an exponential moving average of the Hessian diagonal for adaptive preconditioning of the gradient vector.

• New algorithms for loss balancing: Three new loss balancing algorithms, namely Grad Norm, ReLoBRaLo (Relative Loss Balancing with Random Lookback), and Soft Adapt are implemented. These algorithms dynamically tune the loss weights based on the relative training rates of different losses. Also, Neural Tangent Kernel (NTK) analysis is implemented. NTK is a neural network analysis tool that indicates the convergent speed of each component. It will provide an explainable choice for the weights for different loss terms. Grouping the MSE of the loss allows computation of NTK dynamically.

• Sobolev (gradient-enhanced) training: Sobolev training of neural networks solvers incorporate derivative information of the PDE residuals into the loss function.

• Hydra Configs: A big part of model development is hyperparameter tuning that requires performing multiple training runs with different configurations. Usage of Hydra within Modulus Sym allows for more extensibility and configurability. Certain components of the training pipeline can now be switched out for other variants with no code change. Hydra multi-run also allows for better training workflows and running a hyperparameter sweep with a single command.

• Post-processing: Modulus Sym now supports new Tensorboard and VTK features that will allow better visualizations of the Model outputs during and after training.

Feature Summary

• Improved stability in multi-GPU/multi-Node implementations using linear-exponential learning rate and utilization of TF32 precision for A100 GPUs

• Physics types:

  • Linear Elasticity (plane stress, plane strain and 3D)

  • Fluid Mechanics

  • Heat Transfer

  • Coupled Fluid Thermal

  • Electromagnetics

  • 2D wave propagation

  • 2 Equation Turbulence Model for channel flow

• Solution of differential equations:

  • Ordinary Differential Equations

  • Partial Differential Equations

    • Differential (strong) form

    • Integral (weak) form

• Several Neural Network architectures to choose from:

  • Fully Connected Network

  • Fourier Feature Network

  • Sinusoidal Representation Network

  • Modified Fourier Network

  • Deep Galerkin Method Network

  • Modified Highway Network

  • Multiplicative Filter Network

  • Multi-scale Fourier Networks

  • Spatio-temporal Fourier Feature Networks

  • Hash Encoding Network

  • Super Resolution Net

• Neural Operators

  • Fourier Neural Operator (FNO)

  • Physics Informed Neural Operator (PINO)

  • Adaptive Fourier Neural Operator (AFNO)

  • DeepONet

• Other Features include:

  • Global mass balance constraints

  • SDF (Signed Distance Function) weighting for PDEs in flow problems for rapid convergence

  • Exact mass balance constraints

  • Exact boundary condition imposition

  • Global and local learning rate annealing

  • Global adaptive activation functions

  • Halton sequences for low discrepancy point cloud generation

  • Gradient accumulation

  • Time stepping schemes for transient problems

  • Temporal loss weighting and time marching for continuous time approach

  • Importance Sampling

  • Homoscedastic task uncertainty quantification for loss weighting

  • Exact boundary condition imposition

  • Sobolev (gradient-enhanced) training

  • Criteria based training termination

  • Utilities for Nondimensionalization

  • Causal weighting scheme

  • Selective Equation Term Suppression

  • FuncTorch Integration

  • L2-L1 loss norm decay

  • Meshless Finite Differentiation

  • CUDA Graphs Integration

  • Loss balancing schemes:

    • Grad Norm

    • ReLoBRaLo

    • Soft Adapt

    • NTK

  • Parameterized system representation for solving several configurations concurrently

  • Transfer learning for efficient surrogate based parameterizations

  • Polynomial chaos expansion method for accessing how the model input uncertainties manifest in its output

  • APIs to automatically generate point clouds from boolean compositions of geometry primitives or import point clouds for complex geometry (STL files)

  • STL point cloud generation from superfast ray tracing method with uniformly emanating rays using Fibonacci sphere. Points categorized as inside, outside and on the surface, SDF, and its derivative calculation

  • Logically separate APIs for physics, boundary conditions and geometry consistent with traditional solver datasets

  • Support for optimizers: Modulus Sym supports 30+ optimizers including the built-in PyTorch optimizers and optimizers from the torch-optimizer library. Support for AdaHessian optimizer

  • Hydra configs to allow for easy customization, improved accessibility and hyperparameter tuning

  • Tensorboard plots to easily visualize the outputs, histograms, etc. during training

Known Issues

• Tiny CUDA NN models are only supported on Ampere or newer GPU architectures using the Docker container.

• Multi-GPU training not supported for all use cases of Sequential Solver.