# A Predictive Model for Convective Flows Induced by Surface Reactivity Contrast

## TL;DR

This paper introduces an analytical model that predicts convective flows caused by surface reactivity gradients, aiding in understanding catalytic processes and nanomotor speeds.

## Contribution

The study presents a simple analytical model for predicting electro and diffusio osmotic flows induced by reactive surface patterns, validated against numerical solutions.

## Key findings

- Model accurately predicts induced potentials and velocities.
- Flow predictions match direct numerical simulations.
- Applicable to catalytic enhancement and nanomotor speed estimation.

## Abstract

Concentration gradients in a fluid along a reactive surface due to contrast in surface reactivity generate convective flows. These flows result from contributions by electro and diffusio osmotic phenomena. In this study we have analyzed reactive patterns that release and consume protons, analogous to bimetallic catalytic conversion of peroxide. Here, we present a simple analytical model that accurately predicts the induced potentials and consequent velocities in such systems over a wide range of input parameters. Our model is tested against direct numerical solutions to the coupled Poisson, Nernst-Planck, and Navier-Stokes equations. Our analysis can be used to predict enhancement of mass transport and the resulting impact on overall catalytic conversion, and is also applicable to predicting the speed of catalytic nanomotors.