Carbonate Cake Filtration Simulation Using the Eulerian Multiphase Model — ANSYS Fluent Tutorial

Description

Filtration is one of the most widely used physical separation processes in industry, essential for removing solid particles from liquids in applications such as water treatment and purification, chemical processing, and environmental remediation. As filtration proceeds, the separated solids accumulate on the filter surface and form a layer known as the filter cake. While the cake itself can improve capture efficiency, its continuous growth increases flow resistance and gradually reduces the performance of the filtration unit — making accurate prediction of cake formation a key concern in filter design and operation.

This tutorial, part of the Clean Water: Beginner CFD Training Package, presents a complete simulation of carbonate cake filtration in ANSYS Fluent. The model captures the interaction between three phases — water as the carrier fluid, suspended carbonate particles, and the carbon filter medium — allowing you to study how carbonate particles are captured by the filter and how the cake layer develops over time. Whether you are a process engineer, a CFD specialist, or a chemical engineering student, this project provides a practical foundation for simulating industrial separation processes.

Methodology

The filtration unit geometry is created in ANSYS Design Modeler, and a high-quality structured mesh is generated in ANSYS Meshing to ensure accurate resolution of the multiphase flow field.

The simulation is built on the Eulerian multiphase model, the most rigorous approach for modeling interpenetrating phases with strong momentum coupling. Key elements of the setup include:

• Activating the Granular and Packed Bed options to represent the solid carbonate phase and the stationary filter medium

• Defining granular phase property models for the granular temperature calculation

• Applying interphase momentum exchange mechanisms, including drag, lift, and virtual mass forces between each phase pair

The energy equation is enabled to compute the temperature distribution within the domain, and the Ranz-Marshall correlation is used to model heat transfer between the water and the filter phase. Turbulence is modeled with the standard k-epsilon model, providing a robust balance of accuracy and computational cost for this class of flow.

Analysis

At the end of the solution process, contours of phase volume fraction, temperature, and velocity are extracted and interpreted. The results show how the carbonate concentration changes across the filter as particles are progressively captured by the carbon medium, confirming the physical separation of the solid phase from the water stream. The temperature profile of the feed water through the unit is also examined, illustrating the thermal interaction between the flow and the filter.

Most importantly, the simulation reveals the dynamics of cake layer formation: carbonate particles accumulate on the filter surface, the cake thickness grows over time, and the added flow resistance begins to affect the filtration performance. These insights demonstrate how CFD can be used to evaluate filter efficiency, optimize filtration unit design, and support decisions on filter maintenance and scale-up for industrial clean-water applications.