The coefficient of permeability increases when the viscosity of fluid decreases.


Permeability is a measure of a material's ability to allow fluids to pass through it. It is an important parameter in determining the rate at which fluids can flow through a porous medium, such as soil or rock. The coefficient of permeability (k) is a constant that quantifies the permeability of a material.


Viscosity is a measure of a fluid's resistance to flow. It is influenced by factors such as temperature and the nature of the fluid. When the viscosity of a fluid decreases, it becomes less resistant to flow, and this has a direct impact on the permeability of the material through which the fluid is flowing.

- Fluid Flow: When a fluid flows through a porous medium, it experiences resistance due to the interaction between the fluid and the solid particles that make up the medium. This resistance is affected by the viscosity of the fluid. When the viscosity decreases, the fluid can flow more easily through the pores of the medium, resulting in an increase in permeability.

- Pore Size: The viscosity of a fluid also affects the size of the pores through which it can flow. When the viscosity decreases, the fluid can flow through smaller pores, increasing the effective pore size and therefore the permeability of the medium.

- Darcy's Law: Darcy's law is a fundamental equation that describes fluid flow through a porous medium. It states that the rate of flow is proportional to the permeability of the medium and the pressure gradient driving the flow. When the viscosity of the fluid decreases, the flow rate increases for the same pressure gradient, indicating an increase in permeability.

- Experimental Observations: Numerous laboratory experiments have shown that the coefficient of permeability increases when the viscosity of the fluid decreases. These experiments involve measuring the flow rate of fluids through different materials under controlled conditions.

In conclusion, the coefficient of permeability increases when the viscosity of the fluid decreases. This is because a less viscous fluid can flow more easily through the pores of a porous medium, resulting in increased permeability.