What type of PDEs (partial differential equations) are the following:
- $\frac{\mu}{K}\textbf{u} + \frac{\partial \textbf{u}}{\partial t} = -\nabla p $ (Darcy's law),
- $\frac{\partial c} {\partial t} + \textbf{u} \cdot \nabla c= \nabla^2 c$ (convection-diffusion equation).
Next how many boundary conditions and initial conditions does a PDE require to solve $?$ for example
This is not a complete answer to your question. So one may not be satisfied to it.
Hint: Write it done in its full expansion and see.
It is a combination of parabolic and hyperbolic partial differential equation.
Number of initial and boundary conditions will depend on the region where you have modeled your equations, co-ordinate system you are using, and the method of solution (Analytical, Numerical using finite difference method, Finite element method etc.) you are using.