Created By : Abhinandan Kumar

Reviewed By : Phani Ponnapalli

Last Updated : May 17, 2023

Darcy's law is used to calculate the porosity and permeability of a porous material with a fluid moving through it in this porosity and permeability calculator. The earth sciences use this equation to find out how water, oil, gas, and other substances move through the earth's layers.

Pressure in
Pressure out
Distance (L)
Area (A)
Discharge (Q)
Viscosity (μ)
Residence (t)
Choose the unit you want to calculate in

Porosity - Definition

"What is porosity ?" we ask. We're trying to figure out how much of a substance's volume is empty compared to the space taken up by solid things. The amount of free area per unit volume of material is referred to as porosity.

The porosity of a substance determines how well it permits fluid to pass through it when utilising the Darcy equation. The porosity of a material determines how easily fluids flow through it, but only when the voids are adequately connected. Let's start with the fluid flow porosity equation, then unpack and interpret it.

Porosity formula: ╧ò = Qt/AL

  • Where, ╧ò = Porosity of material
  • Qt = Time takes for a fluid to traverse the distance L
  • A = Cross-sectional area

The more porous a material is, the faster it discharges for a given volume of material, according to this equation. The term "porosity" refers to a quantity that has no dimensions.

How to determine Permeability using Darcy's law?

Darcy's law is an approximation that is widely used in the earth sciences to determine a material's properties. It simulates fluid movement through porous media. Darcy's law can be written as Q= kA.Δp/ μL

  • Where, Q – Discharge rate
  • k – Permeability of the material
  • A – cross-sectional area of the material
  • μ – Dynamic viscosity of the fluid
  • L – Fluid traveling distance through the material
  • Δp – Pressure difference on either side of the material.

This equation may be rearranged to get the permeability in terms of the other quantities that can be measured in experiments: k = QμL/AΔp

The darcy (d) or millidarcy is the commonly used unit for permeability (md). The darcy unit's dimensions are L^2 (length squared). As a result, permeability can also be expressed in SI units as m^2 (meters squared) – The area of one darcy is 9.87 x 10^-13 m^2.

Porosity vs. Permeability

The quantity of vacant space in a substance is determined by its porosity. The flow of fluids through a material is measured by its permeability. Even though a material has a high porosity, if the voids in it are not connected, fluids will not flow through it, lowering its permeability.

How to use the Porosity and Permeability Calculator?

It's really simple to use our porosity and permeability calculator. The fluid pressure gradient over the material is first defined. You have the option of entering the pressure on both sides or immediately entering the pressure differential.

Fill the missing value with the following terms:

  1. The length of time it takes for the fluid to flow through a substance.
  2. The material's cross-sectional area.
  3. The rate at which fluid leaves the substance.
  4. The fluid's viscosity is a measure of how thick it is.

Input the residence time, which is the time it takes for the fluid to pass through the material, to determine the porosity. And there you have it: your substance's porosity.

How to calculate the Permeability Coefficient?

Darcy's law equation is used to determine the permeability of a porous material:

  • Step 1: Multiply the fluid dynamic viscosity, discharge rate, and distance traveled.
  • Step 2: Divide the value from Step 1 by the material's cross-sectional area multiplied by the pressure differential on both sides.
  • Step 3: The fluid passes through the substance because of its permeability.

Become familiar with plenty of similar concepts of physics along with well designed calculator tools complementing the concept on a trusted reliable portal for all your needs.

FAQs on Porosity and Permeability Calculator

1. What is Darcy's Velocity?

The rate of fluid flow per unit of the cross-sectional area of a porous medium is known as Darcy velocity. It is determined by the material's porosity as well as the pressure differential that drives the fluid movement.

2. What is the purpose of measuring permeability?

The ease with which a fluid flows through a porous substance is referred to as permeability. High permeability materials allow for easy flow, whilst low permeability materials resist flow. When choosing materials for resin infusion, it's crucial to strike a balance between permeability and the completed composite's qualities.

3. How do permeability and porosity relate to one other?

The ability of a rock to hold a fluid is measured by its porosity. The free space in a rock divided by the total rock volume is the formula (solid and space). The ease with which a fluid can pass through a porous substance is measured by permeability.

4. What is the significance of porosity and permeability?

The porosity and permeability of rocks are essential factors in evaluating which rocks are suitable for use as reservoirs. A porous and permeable rock would make an excellent reservoir rock because it allows oil and gas to migrate up through the pores and closer to the surface, where it can be retrieved.

5. When it comes to porosity and permeability, how does grain size play a role?

The finer grains tend to occupy the spaces between the bigger grains in poorly sorted sediments with a greater range of particle sizes, resulting in decreased porosity. Primary porosity in crystalline rocks like granite can range from less than 1% to over 55% in some soils.