## STEM

#### What is viscosity

Tagged:

• prajput
Ansys Employee

Hello,

What is fluid viscosity?

Thank you.

Ansys Employee

Viscosity is the measure of the fluid resistance to deformation. When fluids move they tend to deform continuously. This is due to some internal forces (or better stresses) that we can call shear stresses. For some fluids, the deformation is proportional to the magnitude of the shear stresses. These fluids are known as 'Newtonian Fluids'. The SI units of viscosity are kg / (m s) or (Pa s).

Have a look at our Ansys Innovation Courses. In particular you check out these two courses that discuss about viscosity:

## What Are Fluids? | Ansys Innovation Courses

https://courses.ansys.com/index.php/courses/what-are-fluids/
What are fluids? Get the answer in this free course by examining the physical properties of fluids and defining the many types of fluid flows.

## Exploring the Physics of Drag | Ansys Innovation Courses

https://courses.ansys.com/index.php/courses/exploring-drag-and-physics/
This fun and engaging course will teach you about the basics of aerodynamics, the phenomenon known as drag, and how airplanes stay up in the air.

• prajput
Ansys Employee

Thank you for the response! Why are there two types of viscosities? How do you differentiate between them?

Thank you!

Ansys Employee

Hi @prajput , the definition provided by my colleague is for the dynamic viscosity of the fluid. When you divide this number with the fluid density, you will obtain the kinematic viscosity.

Mathematically,

nu = mu / rho

where,

nu refers to kinematic viscosity,

mu refers to dynamic viscosity, and

rho refers to fluid density

The SI unit is m^2/s.

Thank you.?