This work presents multiscale modeling of blood flow and polymer suspensions which requires the use of heterogeneous modeling approaches. A hybrid method based on coupling the Molecular Dynamics (MD) method, the Dissipative Particle Dynamics (DPD) method, and the incompressible Navier-Stokes (NS) equations is developed and is called the Triple-Decker algorithm. MD, DPD, and NS are formulated in separate subdomains and are coupled via an overlapping region by communicating state information at the subdomain boundaries. The triple-decker algorithm is verified for several prototype flows such as Couette, Poiseuille, and lid-driven cavity flow.

A three-dimensional multiscale red blood cell (RBC) model is developed and is able to predict RBC mechanics, rheology, and dynamics in agreement with experiments. Based on an analytic theory, the modeled membrane properties can be uniquely related to the experimentally established RBC macroscopic properties without any adjustment of parameters. The developed model is applied to modeling infected RBCs in malaria where RBC membrane properties can dramatically change. Blood flow is simulated in microtubes for different diameters and hematocrit values. The blood flow model captures the well-known Fahraeus and Fahraeus-Lindquist effects and cell-free layers measured in experiments. Blood flow in malaria is characterized by the adhesion of infected RBCs to the vascular endothelium. The adhesive dynamics of infected RBCs in malaria is simulated based on the stochastic bond formation/dissociation model and compares well with experimental observations.

Depletion layers in dilute polymer solutions in micro- and nano-channels are investigated for various conditions and compare well with the asymptotic lattice theory solution of depletion near a repulsive wall. In Poiseuille flow, polymer migration across the streamlines results in two symmetric off-center peaks in the center-of-mass distribution which identify the preferred chain positions across the channel. Steady state rheological properties of semi-dilute polymer solutions and melts are obtained with the Reverse Poiseuille flow (RPF) which is demonstrated to be an accurate and convenient virtual rheometer for complex fluids. For isothermal solutions the material functions satisfy the principle of time-concentration superposition, while for undiluted chains the temperature dependence is reconciled by the principle of time-temperature superposition.