  Self-training techniques have shown remarkable value across many deep
learning models and tasks. However, such techniques remain largely unexplored
when considered in the context of learning fast solvers for systems of partial
differential equations (Eg: Neural Operators). In this work, we explore the use
of self-training for Fourier Neural Operators (FNO). Neural Operators emerged
as a data driven technique, however, data from experiments or traditional
solvers is not always readily available. Physics Informed Neural Operators
(PINO) overcome this constraint by utilizing a physics loss for the training,
however the accuracy of PINO trained without data does not match the
performance obtained by training with data. In this work we show that
self-training can be used to close this gap in performance. We examine
canonical examples, namely the 1D-Burgers and 2D-Darcy PDEs, to showcase the
efficacy of self-training. Specifically, FNOs, when trained exclusively with
physics loss through self-training, approach 1.07x for Burgers and 1.02x for
Darcy, compared to FNOs trained with both data and physics loss. Furthermore,
we discover that pseudo-labels can be used for self-training without
necessarily training to convergence in each iteration. A consequence of this is
that we are able to discover self-training schedules that improve upon the
baseline performance of PINO in terms of accuracy as well as time.
