What is a Porous medium?
A porous medium is a substance that contains pores or spaces between solid material through which liquid or gas can pass. Examples of naturally occurring porous media include sand, soil, and some types of stone, such as pumice and sandstone. Sponges, ceramics, and reticulated foam are also manufactured for use as porous media. The possible applications of these materials in science, industry and everyday life are vast, although they are perhaps most commonly used as filters. Physically, a porous medium can be distinguished from other materials — including other porous media — by its porosity, or the size of its pores. Materials with low porosity are less permeable and typically have smaller pores, making it more difficult for gas or liquid to pass through them, while materials with high porosity have large pores and are easily permeated. Porosity is an important consideration in filtering since if particles must be removed by a porous medium, the pores must be small enough to effectively trap them. Geologists also consider the porosity of the surrounding stone and soil when conducting observations of oil and natural gas reservoirs. Natural gas trapped in low-porosity stone is known as “tight gas” and is more difficult to access than other reserves.
CFD simulations inside a porous medium in ANSYS Fluent software
The porous media model can be used for a wide variety of single-phase and multiphase problems, including flow through packed beds, filter papers, perforated plates, flow distributors, and tube banks. When you use this model, you define a cell zone in which the porous media model is applied and the pressure loss in the flow is determined. Heat transfer through the medium can also be represented, subject to the assumption of thermal equilibrium between the medium and the fluid flow.
The porous media models for single-phase flows and multiphase flows use the Superficial Velocity Porous Formulation as the default. ANSYS FLUENT calculates the superficial phase or mixture velocities based on the volumetric flow rate in a porous region. However, it is important to note the following for multiphase flow:
- In the Eulerian multiphase model (this section in the separate Theory Guide), the general porous media modeling approach, physical laws, and equations described below are applied to the corresponding phase for mass continuity, momentum, energy, and all the other scalar equations.
- The Superficial Velocity Porous Formulation generally gives good representations of the bulk pressure loss through a porous region. However, since the superficial velocity values within a porous region remain the same as those outside the porous region, it cannot predict the velocity increase in porous zones and thus limits the accuracy of the model.
Porous media are modeled by the addition of a momentum source term to the standard fluid flow equations. The source term is composed of two parts: a viscous loss term (Darcy), and an inertial loss term.
Where is the source term for the ith (x, y, or z) momentum equation, is the magnitude of the velocity, and D and C are prescribed matrices. This momentum sink contributes to the pressure gradient in the porous cell, creating a pressure drop that is proportional to the fluid velocity (or velocity squared) in the cell.
MR-CFD, an expert in the field of porous medium simulations
Having several years of experience in simulating a wide range of problems in various CFD fields using Fluent software, the MR-CFD team is ready to offer extensive modeling, meshing, and simulation services. Simulation Services for acoustical simulations are categorized as follows:
- Premixed Combustion in Porous Zone
- Capillary Action (wicking), Water flows in porous media
- Multiphase Flow in Porous Medium, Filter Cake Formation
- Water infiltration into a porous concrete block
- Porous Mixer for Increasing the Heat Transfer of Nanofluid
- Non-Equilibrium Heat transfer in Porous Aluminum Foam Heat Sink
You may find the related products in the aforementioned categories in our CFD shop by clicking on the following link:
Our services are not limited to the mentioned subjects, and the MR-CFD team is ready to undertake different and challenging projects in the CFD simulation of porous medium field ordered by our customers. You can consult with our experts freely and without charge at first, and then order your project by sending the details of the problem to us using the following address.
By entrusting your project to the MR-CFD team, you will not only receive the related project’s files (Geometry, Mesh, Fluent files). Also, you will be provided with an extensive tutorial video demonstrating how you can create the geometry, mesh, and define the needed settings in the Fluent software all by yourself. And these all come with post-technical support from the MR-CFD team.
MR-CFD experts are ready to fulfill every Computational Fluid Dynamic (CFD) needs. Our service includes both industrial and academic purposes considering a wide range of CFD problems. MR-CFD serves in three main categories of ANSYS Fluent Consultation, ANSYS Fluent Training, and ANSYS Fluent Project Simulation. MR-CFD company has gathered experts from various engineering fields to ensure the quality of CFD services. Your CFD project would be done in the shortest time, with the highest quality and appropriate cost.
Porosity ranges from a low percentage in dense shale and sandstone to about 50% in the sand and up to 70% in clay. Artificial materials can be even more porous. For example, reticulated foam, a porous medium used in air conditioner filters and cosmetic applicators, has a porosity of up to 98%.