Fix error with RNN example

[ktangsali]

PhysicsNeMo Pull Request

Description

The navier_stokes_rnn.py example's prepare_data function was incorrectly slicing 16 input timesteps when One2ManyRNN expects only 1 timestep—this bug was previously masked because the old model lacked shape validation and silently ignored extra timesteps. Fixed the data slicing logic to correctly prepare 1 input timestep for one2many mode and 16 input timesteps for seq2seq mode, aligning with the models' expected input shapes.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• The CHANGELOG.md is up to date with these changes.
• An issue is linked to this pull request.
• If I am implementing a new model or modifying any existing model, I have followed the Models Implementation Coding Standards.

Dependencies

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[greptile-apps]

Greptile Overview

Greptile Summary

Fixed critical bug in prepare_data function where input timesteps were incorrectly sliced from the data array, causing shape mismatches with the RNN models.

• Changed input slicing from input_nr_tsteps:input_nr_tsteps+predict_nr_tsteps to 0:input_nr_tsteps to correctly prepare 1 timestep for One2ManyRNN and 16 timesteps for Seq2SeqRNN
• Changed output slicing from input_nr_tsteps+predict_nr_tsteps:input_nr_tsteps+2*predict_nr_tsteps to input_nr_tsteps:input_nr_tsteps+predict_nr_tsteps to get the correct prediction window
• The bug was previously masked because the old model implementation lacked shape validation and silently ignored extra timesteps
• The fix aligns with the models' input validation requirements: One2ManyRNN expects exactly 1 timestep (validated in rnn_one2many.py:241-245), while Seq2SeqRNN expects nr_tsteps timesteps (validated in rnn_seq2seq.py:242-247)

Important Files Changed

Filename	Overview
examples/cfd/navier_stokes_rnn/navier_stokes_rnn.py	Corrected data slicing in prepare_data to properly align input/output timesteps with model requirements (1 timestep for one2many, 16 for seq2seq)

[greptile-apps]

_{1 file reviewed, no comments}

_{Edit Code Review Agent Settings | Greptile}

[coreyjadams]

LGTM

[ktangsali]

/blossom-ci

[coreyjadams]

FYI failing doctest fixes are in the pipeline.

[ktangsali]

/blossom-ci