Pressure gradients fail to predict diffusio-osmosis.

Area of Science:

• Physical Chemistry
• Fluid Dynamics
• Computational Science

Background:

• Diffusio-osmotic flow is fluid movement driven by concentration gradients at interfaces.
• Accurate simulation methods are crucial for understanding interfacial phenomena.

Purpose of the Study:

• To evaluate and compare different numerical methods for calculating diffusio-osmotic flow.
• To validate computational approaches against direct non-equilibrium molecular dynamics simulations.

Main Methods:

• Numerical simulations of diffusio-osmotic flow.
• Comparison of methods based on chemical potential gradients and pressure tensor gradients.
• Reference calculations using direct non-equilibrium molecular dynamics (NEMD).

Main Results:

• The method using chemical potential gradients as external forces aligns with NEMD results.
• The approach calculating pressure tensor gradients deviates from direct simulation data.
• Supports the diffusio-osmotic flow model proposed by Marbach et al.

Conclusions:

• The chemical potential gradient method is a reliable approach for simulating diffusio-osmotic flow.
• The pressure tensor gradient method is not suitable for accurately capturing these flows.
• Numerical simulations provide valuable insights into interfacial fluid dynamics.