This book addresses the key issues in the modeling and simulation of diffusive processes from a wide spectrum of different applications across a broad range of disciplines. Features: discusses diffusion and molecular transport in living cells and suspended sediment in open channels; examines the modeling of peristaltic transport of nanofluids, and isotachophoretic separation of ionic samples in microfluidics; reviews thermal characterization of non-homogeneous media and scale-dependent porous dispersion resulting from velocity fluctuations; describes the modeling of nitrogen fate and transport at the sediment-water interface and groundwater flow in unconfined aquifers; investigates two-dimensional solute transport from a varying pulse type point source and futile cycles in metabolic flux modeling; studies contaminant concentration prediction along unsteady groundwater flow and modeling synovial fluid flow in human joints; explores the modeling of soil organic carbon and crop growth simulation.