Dynamic Viscosity

The Dynamic Viscosity calculator computes the dynamic viscosity based on the shearing stress (F/A) and the velocity gradient (Δv/Δz).

INSTRUCTIONS: Choose units and enter the following:

• (F) This is the shearing force
• (A) This is the surface area
• (Δv) This is the change in velocity.
• (Δz) This is the change in height.

Dynamic Viscosity (η):  The calculator returns the dynamic viscosity in kg/(m·s).  However this can be automatically converted to compatible units via the pull-down menu.

The Math / Science

Viscosity is simply the resistance to the flow of a fluid.  Technically, Dynamic Viscosity is the ratio of shearing stress and the velocity gradient of a fluid.  The formula for dynamic viscosity is:

      η =  (F / A)  /  (Δv / Δz)

where:

• η is the dynamic viscosity
• F is the force
• A is the surface area
• Δv is the change in velocity
• Δz is the change in height

Note that F/A is shearing stress, and Δv/Δz is the velocity gradient.