First Steps
 

Hi there, I'm fairly new to Computation Fluid Dynamics and the engineering concepts as a whole and I've found myself without answers for a few questions.

I understand that the basic idea is to model the continuous domain into a discrete domain usually by using a grid or mesh. I'm particularly interesting in the 3D discretization where the mesh is made up of hexahedral, prismatic or tetrahedral (and perhaps other) geometries. So the first step is to define the geometries to be used.

I think, that the next step is to simplify the partial differential equations into a more computational form. Methods include the finite volume, finite element and finite difference methods. I read the page 'Computational Fluid Dynamics' on Wikipedia and it refers to these as discretization methods. I also read this tutorial which suggested the conversion from a differential equation to an algebraic equation (but it was within a 1D domain): http://courses.cit.cornell.edu/fluent/cfd/intro.pdf but I gather that it's also to decrease the order for computational processing.

There is also a turbulence model that helps to describe the seemingly 'random' behaviour of particles.

What I'm a bit confused about is how the equations are solved over the geometries of the mesh. Suppose I have a hexahedral celled mesh... would the equations be different from a mesh with tetrahedral cells? Is it the discretization method that adapts the equations to the chosen geometries? The equations I mention here refer to the governing mass and momentum equations for the flow.

Just a bit on what I'm doing: trying to model the flow of air of land for use in a fire spread model.

Any suggestions/insight/tutorials/examples would be deeply appreciated. I'd particularly like an example of how this is done. Also, any book recommendations that could help in modeling air flow over a terrain would be awesome. I've visited the book guide section of this website and I think the book 'Computational Fluid Dynamics: The Basics with Applications' is a good start?