Zhixin Chen, post-doctoral researcher at the Department of Hydromechanics and Modelling of Hydrosystems of the University of Stuttgart, will give the Pretty Porous Science Lecture #77 on the topic "Quasi-static pore-network modeling for evaporation-driven salt transport and precipitation in porous media".
Date: 11 June 2026
Time: 4 pm
Title: "Quasi-static pore-network modeling for evaporation-driven salt transport and precipitation in porous media"
Speaker: Dr. Zhixin Chen, Department of Hydromechanics and Modelling of Hydrosystems, University of Stuttgart
Location: Multi Media Lab, University of Stuttgart, Pfaffenwaldring 61, 70569 Stuttgart
Abstract
Evaporation-driven salt transport and precipitation in porous media is a highly relevant process in many natural and engineering systems, including salt-affected soils, degradation of porous building materials, saline aquifer CO2 storage, and solar-driven interfacial desalination. At the pore scale, these coupled processes are governed by a complex interplay of capillary invasion, vapor diffusion, liquid redistribution, solute transport, and precipitation. Existing dynamic pore-network models can resolve these mechanisms, but they often suffer from severe time-step restrictions and high computational costs. At the same time, conventional quasi-static pore-network models are computationally more efficient, yet they usually cannot capture convective solute transport during drying and invasion events in a physically consistent way.
We will present a novel quasi-static pore-network modeling framework for evaporation-driven salt transport and precipitation. The model adopts a time-splitting strategy in which vapor diffusion and solute diffusion are treated as time-dependent processes, while liquid redistribution and the associated capillary events are represented as instantaneous processes. A central innovation of this work is the derivation of a time-integrated liquid-flux approximation during redistribution events, which makes it possible to quantify convective solute transport within a quasi-static framework. This addresses an important limitation of existing quasi-static pore-network approaches.
The framework was validated against a fully implicit dynamic pore-network model for both pure-water and brine evaporation in one-, two-, and three-dimensional pore networks. The results showed excellent agreement. At the same time, the quasi-static model achieved substantially improved computational efficiency, being approximately one order of magnitude faster than the dynamic approach for identical time steps. The framework was also successfully applied to a large three-dimensional pore network, demonstrating its potential for simulations approaching representative elementary volume (REV) scales. By preserving essential pore-scale physics while drastically reducing computational cost, the framework is well-suited for development of improved constitutive relationships for REV-scale models and derivation of upscaling strategies for evaporation-driven salt precipitation.
AboutZhixin Chen
Zhixin Chen received his Bachelor's degree in Civil Engineering from Hunan University and obtained his PhD in 2024 from Tsinghua University. His doctoral research focused on the remediation mechanisms and multi-field numerical simulation of thermal desorption remediation for organically contaminated soil. He is currently a postdoctoral researcher at the Institute for Modelling Hydraulic and Environmental Systems (IWS), University of Stuttgart. His current work focuses on the multiscale modeling of evaporation-driven salt precipitation in porous media. In particular, he aims to bridge pore-scale physics and continuum-scale descriptions by developing efficient and physically consistent modeling frameworks.