1,269 research outputs found
CFDNet: a deep learning-based accelerator for fluid simulations
CFD is widely used in physical system design and optimization, where it is
used to predict engineering quantities of interest, such as the lift on a plane
wing or the drag on a motor vehicle. However, many systems of interest are
prohibitively expensive for design optimization, due to the expense of
evaluating CFD simulations. To render the computation tractable, reduced-order
or surrogate models are used to accelerate simulations while respecting the
convergence constraints provided by the higher-fidelity solution. This paper
introduces CFDNet -- a physical simulation and deep learning coupled framework,
for accelerating the convergence of Reynolds Averaged Navier-Stokes
simulations. CFDNet is designed to predict the primary physical properties of
the fluid including velocity, pressure, and eddy viscosity using a single
convolutional neural network at its core. We evaluate CFDNet on a variety of
use-cases, both extrapolative and interpolative, where test geometries are
observed/not-observed during training. Our results show that CFDNet meets the
convergence constraints of the domain-specific physics solver while
outperforming it by 1.9 - 7.4x on both steady laminar and turbulent flows.
Moreover, we demonstrate the generalization capacity of CFDNet by testing its
prediction on new geometries unseen during training. In this case, the approach
meets the CFD convergence criterion while still providing significant speedups
over traditional domain-only models.Comment: It has been accepted and almost published in the International
Conference in Supercomputing (ICS) 202
Investigation of Compressor Cascade Flow Using Physics- Informed Neural Networks with Adaptive Learning Strategy
In this study, we utilize the emerging Physics Informed Neural Networks
(PINNs) approach for the first time to predict the flow field of a compressor
cascade. Different from conventional training methods, a new adaptive learning
strategy that mitigates gradient imbalance through incorporating adaptive
weights in conjunction with dynamically adjusting learning rate is used during
the training process to improve the convergence of PINNs. The performance of
PINNs is assessed here by solving both the forward and inverse problems. In the
forward problem, by encapsulating the physical relations among relevant
variables, PINNs demonstrate their effectiveness in accurately forecasting the
compressor's flow field. PINNs also show obvious advantages over the
traditional CFD approaches, particularly in scenarios lacking complete boundary
conditions, as is often the case in inverse engineering problems. PINNs
successfully reconstruct the flow field of the compressor cascade solely based
on partial velocity vectors and near-wall pressure information. Furthermore,
PINNs show robust performance in the environment of various levels of aleatory
uncertainties stemming from labeled data. This research provides evidence that
PINNs can offer turbomachinery designers an additional and promising option
alongside the current dominant CFD methods
Finite Volume Graph Network(FVGN): Predicting unsteady incompressible fluid dynamics with finite volume informed neural network
In recent years, the development of deep learning is noticeably influencing
the progress of computational fluid dynamics. Numerous researchers have
undertaken flow field predictions on a variety of grids, such as MAC grids,
structured grids, unstructured meshes, and pixel-based grids which have been
many works focused on. However, predicting unsteady flow fields on unstructured
meshes remains challenging. When employing graph neural networks (GNNs) for
these predictions, the message-passing mechanism can become inefficient,
especially with denser unstructured meshes. Furthermore, unsteady flow field
predictions often rely on autoregressive neural networks, which are susceptible
to error accumulation during extended predictions. In this study, we integrate
the traditional finite volume method to devise a spatial integration strategy
that enables the formulation of a physically constrained loss function. This
aims to counter the error accumulation that emerged in autoregressive neural
networks during long-term predictions. Concurrently, we merge vertex-center and
cell-center grids from the finite volume method, introducing a dual
message-passing mechanism within a single GNN layer to enhance the
message-passing efficiency. We benchmark our approach against MeshGraphnets for
unsteady flow field predictions on unstructured meshes. Our findings indicate
that the methodologies combined in this study significantly enhance the
precision of flow field predictions while substantially minimizing the training
time cost. We offer a comparative analysis of flow field predictions, focusing
on cylindrical, airfoil, and square column obstacles in two-dimensional
incompressible fluid dynamics scenarios. This analysis encompasses lift
coefficient, drag coefficient, and pressure coefficient distribution comparison
on the boundary layers
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