RowSim

Opening · the research premise

Rowing data is usually compressed into numbers on a display: split, watts, stroke rate, a progress bar that finishes when the piece finishes. Useful, and strangely distant from the body that produced them.

RowSim asks a different question. What happens when the feedback lives on the floor around the ergometer and moves with the stroke instead of competing with it?

The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it.
Mark WeiserThe Computer for the 21st Century, 1991

Swift + MetalStudy completed · N=17

Illustrated from the Metal kernels

Four plates. One wake.

Trace, disturb, solve, and restore. Each plate pairs a live field with a diagram of the compute step in FluidCompute.metal. Drag on a plate to steer the diagram—not just highlight it.

FIG. 03.1BACKWARD TRACEMove the fieldadvectx* = x − u(x,t)·Δt

FIG. 03.1BACKWARD TRACE

advectMove the fieldOn the grid: the output cell steps backward along u, lands in a 2×2 neighborhood, bilinear-samples, then writes.

FIG. 03.2RBGS PRESSURE

pressureSolveMake it incompressiblePressure is solved on a checkerboard—red cells, then black—so every update reads neighbors that already finished.

FIG. 03.3GAUSSIAN RIPPLE

force + waveInject a strokeLeft: inject and rings. Right: G(x) with ±σ guides; the solid bar is the width 2σ. Drag the right panel to change σ.

FIG. 03.4VORTICITY FIELD

vorticityConfinementKeep the swirlVorticity (ω) is the curl of velocity—the arrows. Confinement is a small force that reinforces that spin so it is not lost to numerical diffusion.

Governing constraint

∇u0

The pressure projection removes compression from the velocity field. That one constraint is what makes the motion read as fluid—whether the disturbance came from an oar trail, a ripple coupling, or a fingertip on iOS.

Explore all formulas

Table of contents

Follow the wake.

Eight source-grounded chapters move from architecture to fluid dynamics, sensing, implementation, study results, and future work. Every technical claim points back to the repository.

Evidence policy

Physical output separates. Engagement does not.

Seventeen adults rowed the same magenta floor under REB 2025-8251. All seven physical-output measures separated elite from casual; none of the six engagement measures did. The interactive edition sits beside the thesis PDF — it is not a substitute.

Read the study

Source archive

See what the surface is made of.

The interactive edition sits beside the thesis PDF. It is a reading surface over the same archive that supports the thesis: Metal kernels, host code, architecture notes, and the anonymous study results.

Formulas Voyage Thesis & sources

Follow the wake.

Physical output separates. Engagement does not.

See what the surface is made of.