Add doc for suspension viscosity models

docs/source_docs/user_guide/inputs/fluid_model.rst

@@ -53,7 +53,7 @@ The following inputs are defined using the ``fluid`` prefix.
 |                                            | * ``Roscoe`` :cite:p:`roscoe52,krieger59`                  |        |          |
 |                                            |                                                            |        |          |
 |                                            |      :math:`\mu_{susp}=\mu_{mol} \mu^*`, where             |        |          |
-|                                            |      :math:`\mu^*=(max(c1-\varepsilon_s,e^{-9})/c1)^{-c2}` |        |          |
+|                                            |      :math:`\mu^*=(max(c1-\varepsilon_s,10^{-9})/c1)^{-c2}`|        |          |
 |                                            |                                                            |        |          |
 |                                            | * ``ChengLaw`` :cite:p:`cheng03`                           |        |          |
 |                                            |                                                            |        |          |