# Stress tensor

From AMS Glossary

## stress tensor

It has nine components, one for each of the coordinate faces of an imaginary fluid element upon which the stress acts (

*j*=*x*,*y*,*z*) and for each direction in which the stress is directed (*i*=*x*,*y*,*z*) By definition, an inviscid fluid is one in which the six tangential stresses (*i*≠*j*) are zero, and the three normal stresses (*i*=*j*) are equal to the negative of the pressure.