# Validation and calibration of coupled porous-medium and free-flow problems using pore-scale resolved models

## TL;DR

This study validates and calibrates coupled free-flow and porous-medium models using pore-scale simulations, highlighting the importance of interface conditions and effective parameters for accurate predictions in complex geometries.

## Contribution

It introduces a validation framework for coupled Stokes-Darcy models using pore-scale resolved simulations across different geometries and interface conditions.

## Key findings

- Coupled model results are sensitive to interface location and parameters.
- Effective parameters vary with geometrical configuration.
- Validation improves understanding of interface condition impacts.

## Abstract

The correct choice of interface conditions and effective parameters for coupled macroscale free-flow and porous-medium models is crucial for a complete mathematical description of the problem under consideration and for accurate numerical simulation of applications. We consider single-fluid-phase systems described by the Stokes-Darcy model. Different sets of coupling conditions for this model are available. However, the choice of these conditions and effective model parameters is often arbitrary. We use large scale lattice Boltzmann simulations to validate coupling conditions by comparison of the macroscale simulations against pore-scale resolved models. We analyse two settings (lid driven cavity over a porous bed and infiltration problem) with different geometrical configurations (channelised and staggered distributions of solid grains) and different sets of interface conditions. Effective parameters for the macroscale models are computed numerically for each geometrical configuration. Numerical simulation results demonstrate the sensitivity of the coupled Stokes-Darcy problem to the location of the sharp fluid-porous interface, the effective model parameters and the interface conditions.