# PrandtlNumber ([`Case`](index.md))

Defines the constant Prandtl number used by FELiCS for thermal diffusion and heat conduction.

<dl>
  <dt><strong>Type</strong></dt>
  <dd><em>float</em></dd>

  <dt><strong>Default</strong></dt>
  <dd><code>0.71</code></dd>
</dl>

### Example
```json
"Case": {
    "PrandtlNumber": 0.71
}
```

This parameter is mainly relevant for simulations involving thermal transport or compressible flow equations.