Geometric Neural Operators via Lie Group-Constrained Latent Dynamics
Authors: Jiaquan Zhang, Fachrina Dewi Puspitasari, Songbo Zhang, Yibei Liu, Kuien Liu, Caiyan Qin, Fan Mo, Peng Wang, Yang Yang, Chaoning Zhang
Organizations: School of Information and Software Engineering, University of Electronic Science and Technology of China, Chengdu, China · Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China · Institute of Software Chinese Academy of Sciences, Beijing, China · School of Robotics and Advanced Manufacture, Harbin Institute of Technology, Shenzhen, China · Department of Computer Science, University of Oxford, Oxford, United Kingdom
Neural operators offer an effective framework for learning solutions of partial differential equations for many physical systems in a resolution-invariant and data-driven manner. Existing neural operators, however, often suffer from instability in multi-layer iteration and long-horizon rollout, which stems from the unconstrained Euclidean latent space updates that violate the geometric and conservation laws. To address this challenge, we propose to constrain manifolds with low-rank Lie algebra parameterization that performs group action updates on the latent representation. Our method, termed Manifold Constraining based on Lie group (MCL), acts as an efficient plug-and-play module that enforces geometric inductive bias to existing neural operators. Extensive experiments on various partial differential equations, such as 1-D Burgers and 2-D Navier-Stokes, over a wide range of parameters and steps demonstrate that our method effectively lowers the relative prediction error by 30-50% at the cost of 2.26% of parameter increase. The results show that our approach provides a scalable solution for improving long-term prediction fidelity by addressing the principled geometric constraints absent in the neural operator updates.
Figures & tables
Figure 1: Conceptual comparison between common residual updates in existing neural operators vs. our geometric constrained updates. Our method, termed MCL, addresses the challenge of physical law violation in neural operator update by enforcing geometric inductive bias through Lie algebra parameterization.
Figure 2: Framework of our method, termed MCL, when integrated in a neural operator. MCL replaces the standard unconstrained Euclidean space-based update with geometric-constrained updates based on Lie algebra group action. MCL serves as an efficient plug-and-play module for existing neural operators.
Equation
Param.
Step
Model
Model only
Model + MCL
MSE
Rel_L2
Rel_H1
MSE
Rel_L2
Rel_H1
1-D Burgers
0.001
1
FNO
0.000550
0.046626
0.068925
0.000327
0.035689
0.049867
U-NO
0.042886
0.398778
0.415302
0.039507
0.350689
0.367253
GINO
0.003950
0.147548
0.192726
0.003891
0.146621
0.192288
10
FNO
0.000214
0.037893
0.050876
0.000108
0.026429
0.034554
U-NO
0.025308
0.412722
0.417508
0.020423
0.398555
0.404843
Table 1: Evaluation on MCL integration to neural operator models under various equations, parameters, and rollout steps. Best results are in bold .
Figure 3: Prediction error plot of PDEs on FNO (left) and FNO+MCL (right) against true solution.
Figure 4: Evolution of energy (left) and entropy (right) on 1-D Burgers equation with parameter values 0.001 (top), 0.01 (middle), and 0.1 (bottom).
Param.
Step
Model
MSE
Rel_L2
Rel_H1
0.1
1
FNO +MCL
0.000016
0.004433
0.005201
FNO +MLP
0.000019
0.004549
0.005406
25
FNO +MCL
0.000031
0.006246
0.006954
FNO +MLP
0.000034
0.008008
0.008762
1.0
1
FNO +MCL
0.000064
0.008839
0.009975
FNO +MLP
0.000078
0.009654
0.010835
Table 2: Ablation on MCL contribution on 1-D Advection. Best results are in bold .
Model
# of param.
# of param+MCL
% param. add
FNO
23,937
25,221
5.36
U-NO
2,708,673
2,732,234
0.87
GINO
442,194
444,567
0.54
Table 3: Total parameter count of original model vs. integration with MCL.
Rank dim.
Step
MSE
Rel_L2
Rel_H1
3
1
0.000021
0.000020
0.000017
10
0.000003
0.004529
0.004668
25
0.000001
0.003394
0.003454
30
0.000001
0.003382
0.003436
5
1
0.000020
0.008317
0.008839
10
0.000003
0.004339
0.004482
Table 4: Sensitivity test on hyperparameter.
Step
Model
Model only
Model + MCL
MSE
Rel_L2
Rel_H1
MSE
Rel_L2
Rel_H1
1
FNO
0.094958
0.006878
0.007343
0.003067
0.005678
0.006499
U-NO
0.121584
0.090440
0.099027
0.117830
0.085402
0.094537
GINO
0.014434
0.013638
0.021241
0.013268
0.013185
0.020583
3
FNO
0.002689
0.006452
0.007013
0.002607
0.005090
0.005856
U-NO
0.073323
0.040074
0.047294
0.044330
0.037223
0.046833
Table A1 : 2-D Navier-Stokes
Parameter
Model
Model only
Model + MCL
MSE
Rel_L2
Rel_H1
MSE
Rel_L2
Rel_H1
0.01
FNO
0.00057275
2.59687380
2.61742788
0.00019451
1.04014158
1.06347932
U-NO
0.00022823
1.69248305
1.78475725
0.00021132
1.36236886
1.64780834
GINO
0.00106853
5.07440402
5.05898289
0.00106853
5.06830841
5.05290873
0.1
FNO
0.00044092
0.44783878
0.45378846
0.00021056
0.24423277
0.25018481
U-NO
0.00022993
0.33987113
0.34327716
0.00023840
0.15001997
0.16205981
Table A2 : 2-D Darcy Flow
Parameter
Step
Model
Model only
Model + MCL
MSE
Rel_L2
Rel_H1
MSE
Rel_L2
Rel_H1
0.1
1
FNO
0.000010
0.006182
0.006210
0.000001
0.002284
0.002361
U-NO
0.033765
0.452617
0.476068
0.002880
0.099611
0.104958
GINO
0.000219
0.039598
0.043709
0.000198
0.038372
0.042604
10
FNO
0.000002
0.003629
0.003636
0.000001
0.001334
0.001347
U-NO
0.005832
0.205232
0.225318
0.001769
0.067778
0.070619
Table A3 : 1-D Burgers
Parameter
Step
Model
Model only
Model + MCL
MSE
Rel_L2
Rel_H1
MSE
Rel_L2
Rel_H1
0.1
1
FNO
0.000037
0.005690
0.006920
0.000016
0.004433
0.005201
U-NO
0.002880
0.099611
0.104958
0.002003
0.069950
0.079686
GINO
0.002394
0.060020
0.069219
0.001251
0.038808
0.042497
10
FNO
0.000096
0.009490
0.010656
0.000021
0.004975
0.005685
U-NO
0.005685
0.07778
0.070619
0.001110
0.052989
0.059960
Table A4: 1-D Advection
Step
Model
Model only
Model + MCL
MSE
Rel_L2
Rel_H1
MSE
Rel_L2
Rel_H1
1
FNO
0.000013
0.013330
0.013673
0.000000
0.001321
0.002699
U-NO
0.016053
0.444866
0.447889
0.005528
0.264650
0.269736
GINO
0.269736
0.024395
0.025905
0.000138
0.043518
0.048344
10
FNO
0.000001
0.002817
0.003851
0.000000
0.001211
0.002637
U-NO
0.007221
0.275725
0.276714
0.004055
0.190123
0.190769
Table A5 : 1-D Diffusion
Step
Model
Model only
Model + MCL
MSE
Rel_L2
Rel_H1
MSE
Rel_L2
Rel_H1
1
FNO
0.000021
0.004370
0.008327
0.000010
0.003084
0.005210
U-NO
0.035991
0.172072
0.172072
0.012362
0.101253
0.112789
GINO
0.020287
0.131313
0.149931
0.020275
0.131233
0.150866
10
FNO
0.000015
0.003681
0.005530
0.000004
0.002056
0.003120
U-NO
0.021521
0.137780
0.141981
0.016664
0.117650
0.122598
Table A6 : 2-D Shallow Water
Parameter
Step
FNO + MCL
FNO + MLP
MSE
Rel_L2
Rel_H1
MSE
Rel_L2
Rel_H1
0.1
1
0.000016
0.004433
0.005201
0.000019
0.004549
0.005406
10
0.000021
0.004890
0.005646
0.000023
0.010975
0.010685
25
0.000031
0.006246
0.006954
0.000034
0.008008
0.008762
30
0.000037
0.006938
0.007660
0.000039
0.013526
0.014306
0.4
1
0.000044
0.007285
0.008363
0.000070
0.009049
0.010143
Table A7 : Ablation on 1-D Advection
Figure A1 : Plots on true solution, prediction on NO vs. NO+MCL, and the corresponding error plots on 1-D linear advection equation. Models used for prediction are, from top to bottom, FNO, U-NO, and GINO.
Figure A2 : Plots on true solution, prediction on NO vs. NO+MCL, and the corresponding error plots on 1-D Burgers equation. Models used for prediction are, from top to bottom, FNO, U-NO, and GINO.
Figure A3 : Plots on true solution, prediction on NO vs. NO+MCL, and the corresponding error plots on 1-D diffusion-sorption equation. Models used for prediction are, from top to bottom, FNO, U-NO, and GINO.
Figure A4 : Plots on true solution, prediction on NO vs. NO+MCL, and the corresponding error plots on 2-D Darcy flow equation. Models used for prediction are, from top to bottom, FNO, U-NO, and GINO.
Figure A5 : Plots on true solution, prediction on NO vs. NO+MCL, and the corresponding error plots on 2-D shallow-water equation. Models used for prediction are, from top to bottom, FNO, U-NO, and GINO.
Figure A6 : Plots on true solution, prediction on NO vs. NO+MCL, and the corresponding error plots on 2-D Navier-Stokes equation. Models used for prediction are, from top to bottom, FNO, U-NO, and GINO.
Neural PDE solvers use trainable models to approximate solutions or solution operators for partial differential equations, often with physical constraints.
School of Information and Software Engineering, UESTC · Electronics and Information Convergence Engineering, KHU · School of Computer Science and Engineering, UESTC +4
Program in Applied and Computational Mathematics (PACM), Princeton University, Princeton, 08540, New Jersey, United States. · Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, 08540, New Jersey, United States.