Hamiltonian Neural Network for Fluid Simulation

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Solution Overview

Problem

Current simulation methods for aerial vehicles face challenges in precision and computational cost due to complex interactions with fluid environments, particularly when using physical models like Navier-Stokes equations, which are computationally expensive and require approximations that compromise precision.

Innovation Solution

A multilayer neural network is trained with a specific loss function based on physical reality to predict the current function and velocity field, shifting computational costs to the learning phase and allowing constant computation time during simulation, effectively replacing traditional physical modeling methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If physical models like Navier-Stokes equations are used to simulate fluid behavior, then measurement precision is improved, but computing cost increases significantly

Engineering Contradiction:
Improvesimulation precisionVSAvoidcomputation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-training the neural network offline using high-fidelity Navier-Stokes simulation data and experimental measurements. This preliminary training phase captures complex fluid dynamics patterns, which are then reused during runtime simulations without requiring repeated expensive computations. The network learns from pre-collected data, enabling fast predictions during actual vehicle design iterations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses copying by creating a neural network model that replicates the behavior of complex physical fluid dynamics models. Instead of repeatedly executing computationally intensive Navier-Stokes equations, the system copies the essential fluid behavior patterns into a lightweight neural network that can be evaluated rapidly. This copy maintains sufficient accuracy for design exploration while dramatically reducing computational burden.

Inventive Principle:
Principle #26Copying

2Productivity

If approximations like Reynolds average are used to reduce computing cost, then productivity is improved, but measurement precision deteriorates

Engineering Contradiction:
Improvesimulation speedVSAvoidsimulation precision
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The neural network copies high-fidelity fluid dynamics behavior from expensive physical models and experimental data, preserving accuracy without requiring the computational overhead of traditional approximation methods. The network learns complex nonlinear relationships directly from training data, capturing turbulent flow patterns and separation phenomena that simplified models miss.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent changes the parameter representation by using neural network weights and activations to encode fluid state variables instead of solving differential equations. This parameter transformation allows the system to maintain high precision while achieving computational efficiency, as the network evaluates predefined mathematical functions rather than iteratively solving complex PDEs.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If traditional physical modeling methods are used, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvemodel accuracyVSAvoidcomputational complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent substitutes the mechanical system of solving differential equations with a data-driven neural network model. Instead of relying on explicit physical formulations and iterative numerical solvers, the system uses learned representations from training data to predict fluid behavior. This substitution maintains reliability by grounding the network in physical laws during training while reducing computational complexity during inference.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The complex physical modeling knowledge is copied into the neural network architecture through training on high-fidelity simulation data and experimental measurements. The network internalizes complex fluid-structure interaction patterns, boundary layer behaviors, and turbulent flow characteristics, making them accessible through simple forward propagation without requiring the original complex computational infrastructure.

Inventive Principle:
Principle #26Copying

Data Source

PatentUS20220229948A1Simulation of the behavior of a vehicle in a fluid by Hamiltonian neural network
Publication Date: 2022.07.21 BULL SA
  • US20220229948A1 patent drawing
  • US20220229948A1 patent drawing
  • US20220229948A1 patent drawing

AI summary

A method for simulating the behavior of a system (20) composed of a subsystem (10), such as an aerial vehicle, in a physical environment (21) made of an incompressible fluid, comprisingtraining a multilayer neural network (HNN) by means of a training set associating coordinates (x, y) in said physical environment (21) and respective values of a gradient of the current function (ψ) at said coordinates (x,y), and a loss function configured to minimize an error between a gradient (Sψ) of the output of said neural network and said gradient of the current function;using said neural network to predict a value of a current function (ψ) and a velocity field (u) by providing it with input coordinates.