چكيده به لاتين
The presence of nanoparticles in the fluids inside the porous media leads to improved parameters related to hydrodynamics and heat transfer of the fluid flow. Understanding the behavior of nanoparticles in fluid flow at the pore scale leads to predicting the behavior of nanoparticle flows at larger scales inside the porous medium. Considering that the few existing studies on the simulation of nanofluid flow at the pore scale do not consider the complexities of nanofluid flow with simplifying assumptions such as single-phase fluidity, in this thesis, the simulation of nanofluid flow was investigated with the Eulerian-Lagrangian approach. In addition, due to the importance of nanoparticle attachment in porous media, a computational solver with Eulerian-Lagrangian method was developed in OpenFOAM open-source software by developing a method for nanoparticle attachment. This solver considered influential forces between fluid and nanoparticles, including Brownian motion, drag, buoyancy, and gravity. Also, the effect of influential forces between nanoparticles and the solid surface wall, including van der Waals forces and electrostatic double layers, was investigated. Furthermore, the effect of parameters such as nanoparticle diameter, fluid velocity, pressure gradient, and temperature on nanoparticle deposition ratio (the number of deposited nanoparticles to the injected nanoparticles) was presented. In addition, while introducing two dimensionless parameters N_E1 (magnitude of the surface potential) and N_DL (the ratio of the length of the electrostatic double layer to the radius of the nanoparticle), the effect of these two parameters on the deposition ratio of nanoparticles was investigated. Moreover, using the developed Lagrangian solver, a new solver was developed that can model the effect of nanoparticles on the interfacial tension between two immiscible fluids. At first, the nanofluid flow in a microchannel was investigated. Then, by presenting the foam production process and creating a computing network on microtomographic images, the nanofluid flow in three foams with porosities of 80, 85 and 90% and Beria sandstone with 19.6% porosity was investigated. Furthermore, the effect of nanoparticles on the interfacial tension of immisicible two phase flow was calculated. The results show that increasing the diameter of particles from 30 to 150 nm in air as the base fluid inside a microchannel decreases the deposition ratio of nanoparticles from 0.98 to 0.4. Also, the simulation of the flow of nanoparticles in a single-phase fluid of water inside a microchannel shows that with the increase of N_DLfrom 1 to 100 in the case of N_E1=10 and Re=1, the deposition ratio of nanoparticles increases from 0.003 to 0.189, which results are in accordance with the studies in the literature, and show the accuracy of the performance of the computational solver. In addition, the transport and attachment process of nanoparticles in three foams with different porosities by the pore scale approach shows that with increasing porosity in foams from 80% to 85% and then 90%, for nanoparticles with a diameter of 10 nm and N_E1=1 and N_DL=1, the deposition ratio of nanoparticles decreases from 0.67 to 0.59 and then to 0.56. Also, the results of the interaction of nanoparticles on the interfacial tension in the two-phase fluid show that the amount of interfacial tension decreases with the increase of nanoparticle deposition. For example, with the increase of N_E1 from 1 to 50 and then 100, the minimum amount of interfacial tension decreases from 0.0668 to 0.0657 and then 0.0642 at the same time.
