Hi all, So what I would like to do is to derive the Reynolds Averaged Navier Stokes equations, here i want the \overline operator to mean time average. I started with the convection term:

```
\partial{#}::PartialDerivative;
{u_{#}}::Depends(\partial{#});
\overline{#}::Accent;
\overline{#}::Distributable;
\overline{#}::Depends(\partial{#});
u_{#}}::Depends(\overline{#});
\prime::Symbol;
conv := c_i = \partial_{j}{ \overline{ u_i u_j} };
rl1 := u_{a?} = \overline{u_{a?}} + {u_{a?}}^\prime;
rl2 := \overline{\overline{u_{a?}u_{b?}}} = \overline{u_{a?} u_{b?}}};
substitute(conv, rl1);
distribute(conv);
```

Up to this point, the syntax generates what I want ()although the way it works seems a little inconvenient, as if I was using something wrong, so any tips appreciated!). The problems starts when I want to substitute rl2 into conv:

`substitute(conv, rl2);`

which does nothing (it should just erase one overline from the first term). Am I doing something wrong or is such thing not supported?

Thanks! S