export tutorials changed in db9df8b

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dario-coscia
2025-05-05 08:59:15 +00:00
committed by Dario Coscia
parent a94791f0ff
commit e3d4c2fc1a
23 changed files with 737 additions and 727 deletions

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@@ -2,13 +2,13 @@
# coding: utf-8
# # Tutorial: Modeling 2D Darcy Flow with the Fourier Neural Operator
#
#
# [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/mathLab/PINA/blob/master/tutorials/tutorial5/tutorial.ipynb)
#
#
# In this tutorial, we are going to solve the **Darcy flow problem** in two dimensions, as presented in the paper [*Fourier Neural Operator for Parametric Partial Differential Equations*](https://openreview.net/pdf?id=c8P9NQVtmnO).
#
#
# We begin by importing the necessary modules for the tutorial:
#
#
# In[ ]:
@@ -22,9 +22,11 @@ except:
IN_COLAB = False
if IN_COLAB:
get_ipython().system('pip install "pina-mathlab[tutorial]"')
get_ipython().system('pip install scipy')
get_ipython().system("pip install scipy")
# get the data
get_ipython().system('wget https://github.com/mathLab/PINA/raw/refs/heads/master/tutorials/tutorial5/Data_Darcy.mat')
get_ipython().system(
"wget https://github.com/mathLab/PINA/raw/refs/heads/master/tutorials/tutorial5/Data_Darcy.mat"
)
import torch
import matplotlib.pyplot as plt
@@ -40,15 +42,15 @@ warnings.filterwarnings("ignore")
# ## Data Generation
#
#
# We will focus on solving a specific PDE: the **Darcy Flow** equation. This is a second-order elliptic PDE given by:
#
#
# $$
# -\nabla\cdot(k(x, y)\nabla u(x, y)) = f(x, y), \quad (x, y) \in D.
# $$
#
#
# Here, $u$ represents the flow pressure, $k$ is the permeability field, and $f$ is the forcing function. The Darcy flow equation can be used to model various systems, including flow through porous media, elasticity in materials, and heat conduction.
#
#
# In this tutorial, the domain $D$ is defined as a 2D unit square with Dirichlet boundary conditions. The dataset used is taken from the authors' original implementation in the referenced paper.
# In[2]:
@@ -92,7 +94,7 @@ problem = SupervisedProblem(
# ## Solving the Problem with a Feedforward Neural Network
#
#
# We begin by solving the Darcy flow problem using a standard Feedforward Neural Network (FNN). Since we are approaching this task with supervised learning, we will use the `SupervisedSolver` provided by **PINA** to train the model.
# In[7]:
@@ -146,7 +148,7 @@ print(f"Final error testing {err:.2f}%")
# ## Solving the Problem with a Fourier Neural Operator
#
#
# We will now solve the Darcy flow problem using a Fourier Neural Operator (FNO). Since we are learning a mapping between functions—i.e., an operator—this approach is more suitable and often yields better performance, as we will see.
# In[10]:
@@ -183,7 +185,7 @@ trainer.train()
# We can clearly observe that the final loss is significantly lower when using the FNO. Let's now evaluate its performance on the test set.
#
#
# Note that the number of trainable parameters in the FNO is considerably higher compared to a `FeedForward` network. Therefore, we recommend using a GPU or TPU to accelerate training, especially when working with large datasets.
# In[11]:
@@ -208,13 +210,13 @@ print(f"Final error testing {err:.2f}%")
# As we can see, the loss is significantly lower with the Fourier Neural Operator!
# ## What's Next?
#
#
# Congratulations on completing the tutorial on solving the Darcy flow problem using **PINA**! There are many potential next steps you can explore:
#
#
# 1. **Train the network longer or with different hyperparameters**: Experiment with different configurations of the neural network. You can try varying the number of layers, activation functions, or learning rates to improve accuracy.
#
#
# 2. **Solve more complex problems**: The Darcy flow problem is just the beginning! Try solving other complex problems from the field of parametric PDEs. The original paper and **PINA** documentation offer many more examples to explore.
#
#
# 3. **...and many more!**: There are countless directions to further explore. For instance, you could try to add physics informed learning!
#
#
# For more resources and tutorials, check out the [PINA Documentation](https://mathlab.github.io/PINA/).