Reactive-Di usive Flow Inside Porous Medium

Sammanfattning: Understanding the reactive-di usive turbulent ow inside porous media is interesting in many applications. It could have geochemical applications such as describing the rock dissolution patterns in river beds or the e ect of riparian zones in nitrate attenuation. Other applications could be, e.g. ow over and through vegetation, porous heat exchangers such as metal foams, gas and oil industry, etc. A limited number of studies have been carried out to understand the turbulent ow regime over a porous medium. This might be due to the fact that Darcy's law cannot be applied to turbulent ows. Therefore, the turbulent ow inside/above porous media needs to be done with expensive numerical simulations. This cost is much higher if one wants to solve the problem using Direct Numerical Simulation (DNS) in which the ow eld is completely and directly computed from Navier-Stokes equations. This needs much greater CPU power than other methods such as VANS(Volume-Averaged Navier-Stokes) equations or LES(Large Eddy Simulations), etc; however, solving the Navier-Stokes equation would eliminate any closure problems that appear in turbulence models, which could be considered as an advantage. Furthermore, DNS is able to detect the smallest length scales in turbulence structures which lead to highly accurate results. In addition to Navier-Stokes equations, scalar transport equation is also solved in order to model the transportation of reactive-di usive solutes. In our case, the porous medium is modeled by a packed bed of spheres and an Immersed Boundary Method (IBM) is used to apply the no-slip/no-penetration conditions on the spheres. The main objective of this work is to study how a reactive-di usive scalar is transported through porous media inspired by ows in river beds where micro-organisms and vegetation consume nutrients inside the ow besides the fact that porosity of the river beds a ect these activities as well as ow behavior.