- #1
dRic2
Gold Member
- 884
- 225
Hi,
when working with NS equations the stress tensor can be written as ##\nabla \tau = - \nabla P + \nabla \tau_{v}##, where ##\tau_{v} ## is
\begin{pmatrix}
\tau_{xx} & \tau_{xy} & \tau_{xz} \\
\tau_{xy} & \tau_{yy} & \tau_{yz} \\
\tau_{zx} & \tau_{zy} & \tau_{zz}
\end{pmatrix}
This question was stuck in my mind since last years, but I used to forget to ask: what is the physical interpretation of ##\tau_{xx}##, ##\tau_{yy}##, ##\tau_{zz}##? I know where they come from "mathematically", but I don't get the difference with pressure... I thought viscous stresses could only be like ##\tau_{ij}## with ##i≠j##.
PS: Out of the blue: In a very turbulent flow is it ok to consider ##\tau_{ij} = 0## with ##i≠j##?
Thanks
Ric
when working with NS equations the stress tensor can be written as ##\nabla \tau = - \nabla P + \nabla \tau_{v}##, where ##\tau_{v} ## is
\begin{pmatrix}
\tau_{xx} & \tau_{xy} & \tau_{xz} \\
\tau_{xy} & \tau_{yy} & \tau_{yz} \\
\tau_{zx} & \tau_{zy} & \tau_{zz}
\end{pmatrix}
This question was stuck in my mind since last years, but I used to forget to ask: what is the physical interpretation of ##\tau_{xx}##, ##\tau_{yy}##, ##\tau_{zz}##? I know where they come from "mathematically", but I don't get the difference with pressure... I thought viscous stresses could only be like ##\tau_{ij}## with ##i≠j##.
PS: Out of the blue: In a very turbulent flow is it ok to consider ##\tau_{ij} = 0## with ##i≠j##?
Thanks
Ric