"

{| class=""toccolours collapsible collapsed"" width=""40%"" style=""text-align:left""
!Cauchy stress tensor for a viscous fluid
|-
| For viscous fluids the Cauchy stress tensor  is defined as:

If the fluid is incompressible it follows that:

If the fluid is compressible the assumption above is true, if the viscosity of compression  vanishes:

|}"