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Molecular dynamics simulations (MDSs) are carried on to examine the effects of liquid–nanoparticle (NP) interaction strength, size and number of nanoparticles on the aggregation process in liquid-based nanofluid flowing inside nanochannel. The results show that the increase in liquid–NP interaction strength leads to the reduction of aggregation rate. In addition, the increase in the size and number of NPs leads to more aggregation rate. Predicted results for aggregation trend are in good agreement with experimental data. Likewise, variations of velocity profile and density distribution of liquid particles inside nanochannel are explored.

In the present work, forced convection heat transfer was investigated numerically for the fully developed fluid flow of incompressible viscous laminar flow under the constant wall heat flux in sudden expansion channels. Various fluids were used with different concentration of nanoparticle such as Al₂O₃, TiO₂, ZnO, CuO, SiO₂. These nanoparticles were dispersed with the range of 0.5–2% volume concentrations in pure water to form stable suspensions of nanofluids. The flow assumed to be uniform in the channel inlet and numerical computations were performed for the fully developed laminar flow conditions. Ansys Fluent 16.1 code, based on finite volume approach was used to calculate the governing continuity, momentum and energy equations. Effect of the Re numbers (100$\le$Re$\le$500), nanoparticle volume concentration (0.5%$\le \phi \le$2.0%) and nanofluid type on the flow and heat transfer characteristics such as convective heat transfer coefficient, Nu number, friction factor and pressure drop has been investigated. Al₂O₃/water nanofluid was found better when compared the other references working fluids by means of heat transfer enhancement.

Aerogel is studied numerically using a one-dimensional two-phase flow equations system. A hyperbolic and conservative two-phase flow model is applied to a mixture of porous media containing nanofluids. The application of non-equilibrium mixture behavior between phases is adopted and promoted in this current investigation. By establishing mixture conservation balance laws, finite volume techniques using Godunov methods of centered type are extended to aerogel simulations. Numerical results are compared with other methods providing a remarkable agreement. The computed results demonstrate the key capabilities of this existing mixture model in the resolution of discontinuities in aerogel problems and more reliable than applying a sophisticated single-phase flows with complex property models.