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Numerous models have been proposed to incorporate various equations of state (EOS) into the pseudo potential model. This paper presents an investigation of different EOS types based on the Gong and Cheng model in multiphase-single component flows by the lattice Boltzmann method. Primarily, it is conducted to investigate eight EOS’s classified in four categories; the Shan- Chen EOS, the cubic EOS, the non-cubic EOS, and the cubic and non-cubic combination EOS. The results show that each EOS type results in producing relatively similar spurious currents and has a maximum achievable density ratio. Although by choosing a proper beta parameter for every EOS the simulation errors decrease dramatically, our results show it is impossible to set a constant parameter for the non-cubic EOS. Therefore, a new equation is introduced to predict an efficient beta for the cubic and the Shan- Chen EOS’s. It is also found that the non-cubic, cubic, and non-cubic and cubic combination EOS’s have a wider temperature range and larger density ratios respectively. Hence, we determine a temperature dependent function for the beta parameter prediction instead of using a fixed value for the non-cubic EOS. The results are noticeably in better agreement with those of the Maxwell construction (theoretical results).

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In this article bubbly flow under the specified axial pressure gradient in a curved channel is studied numerically. To do so, a second order parallelized front-tracking/finite-difference method based on the projection algorithm is implemented to solve the governing equations including the full Navier-Stokes and continuity equations in the cylindrical coordinates system using a uniform staggered grid well fitted to the geometry concerned. In the absence of gravity the mid-plane parallel to the curved duct plane, which is the symmetry plane in the single fluid flow inside the curved duct, separates the bubbly flow into two different flow regions not interacting with each other. Twelve bubbles with diameters of 0.125 wall units are distributed in the equally spaced distances from each other. The numerical results obtained indicate that for the cases studied here, the bubbles reach the statistical steady state with an almost constant final orbital motion path due to the strong secondary field. Furthermore, the effects of different physical parameters such as Reynolds number, and curvature ratio on the flow field at the no slip boundary conditions, are investigated in detail.

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In this article, an immiscible two-phase flow in two dimensional ordinary and modified T-junction microchannels is numerically studied. To this approach, the Lattice Boltzmann method with Pseudo-Potential model is used. The accuracy of the present model is examined by the Laplace test, drop contact angle, and drop formation in an ordinary T-junction microchannel. The comparison shows that the present results have good agreement with previous numerical and experimental data. The effects of various parameters including Capillary number, flow rate ratio, width ratio, and drop contact angle on the width of the drop and on the distance between drops for ordinary and modified T-junction microchannels are investigated in details. The results reveal that by simple modifications to the ordinary T-junction, smaller drops and lower distances between them are generated in the comparison of ordinary T-junction geometry under the same conditions. On the other hand, this study demonstrates that the multiphase flows in micro-devices are very sensitive to even small changes in the channel geometry. It also indicates that lattice Boltzmann method with Pseudo-Potential model is an effective numerical technique to simulate the generation of drops in microchannels.

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Controlling the path of drugs movement is one of the processes that can effectively help to treat a variety of diseases. For example, in chemotherapy, small fraction of drug is delivered to the cancer cells and other amounts cause destruction of healthy tissues of body, as a result, before destruction of tumors, the body will be destroyed. Hence we cannot remove tumors from body completely. If we are able to control the path of drugs, we could remove tumors with the least injury. One of the ways through which we can control the movement of the drugs is MDT. In this project, we inspect movement of magnetic particles in the blood and their interactions with consideration of constant magnetic field gradient. After governing its equations and presenting a good model for the forces between particles we simulate these processes in the fluent software. The model we used here is a vein with 8 mm diameter. The simulation was done over 8 cm length of the vein, and from the moment of injection. The base fluid is blood which is considered none-Newtonian fluid. Distribution of magnetic particles in the base fluid has been governed by multiphase approach. The simulation results show that residence time of drug in the presence of magnetic field, increases which in turn increases the possibility of drug absorption.

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In this research work, using the recently introduced entropic constant speed kinetic model and employing the Pseudo-Potential model of Shan and Chen (SC), two phase flow of incompressible and immiscible fluids through porous media is studied. Applications of the entropic kinetic models in simulating multi-phase and multi-component flows have been thoroughly investigated, during the past decade. Lack of an entropy function, in a kinetics based model, implies that the existence of a unique equilibrium state, under all flow conditions and for all positions and times, cannot be guaranteed by the model. Hence, simulation of two multi-phase flows with high density ratios, using the conventional kinetic models (which do not satisfy the second law of thermodynamics) may not yield proper results, due to numerical instabilities. In this research, performing numerical simulations, the accuracy and stability of the recently introduced constant speed kinetic model and the conventional lattice Boltzmann models have been compared with each other. The present simulations include the verification of the Laplace Law and the contact angles and two phase flow through simple channels. In addition to the above, two phase flow in porous media has been simulated and the relative permeability vs wettability has been reported. The obtained results are in excellent agreement with previous results reported by others researchers.

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