Darcy's Law: Calculating Fluid Flow Through Porous Media

Darcy flow describes how well liquid such as water flows through a porous medium, such as soil, paper or anything else that slows the progress of some of the water. By then compensating for the fact that the water is flowing through a porous area, you can accurately calculate its flow. Darcy flow equations are used in situations where pipe is being laid or where groundwater is moving through soil and its speed needs to be calculated accurately.

Instructions

• 1

  Find the hydraulic conductivity. This is the rate at which water flows through the material, but without compensating for the the other elements in the Darcy equation. It is generally expressed in meters per second. You can estimate it by measuring how fast the water is moving, then looking at a hydraulic conductivity table.

• 2

  Find the hydraulic gradient. This is not an actual gradient, but rather the gradient effect that comes from water having to travel through higher and lower pressure areas. To find it, you need to subtract the pressure at the end of the pipe from the pressure at the start of the pipe, then divide the total by the length of the pipe.

• 3

  Find the cross section area of the flow. This is the length of the area in question times its width.

• 4

  Multiply the three figures by one another. Your product is the Darcy flow rate, expressed in a cubic length measurement per second.