Sharif Digital Repository

Significant advances in biotechnology have led to the emergence of a cost-effective way with less ethical issues to study disease, organ functions, tumors, and their response to drugs besides studying on animals. Microfluidic devices and organ on a chip (tumor on a chip) were introduced to remove those obstacles. Organ on a chip is a powerful tool for studying different types of tissues and simulating diseases, especially cancers, for biological and medical applications. Organ (tumor) on a chip is considered as a smaller scale of the real organ or tumor and it causes to the real-time study of tissues and their functions more accurately. In this study, to fabricate a droplet-based... 

Ferrofluids are used in various fields such as drug delivery systems, heat transfer, biotechnology and separation processes. In this study, the splitting of ferrofluid microdroplets in symmetric and asymmetric T-junctions in the presence of a magnetic field has been investigated numerically and experimentally. These studies have shown that the creation of an asymmetric magnetic field can either affect the phenomenon of ferrofluid microdroplet breakup or the volume of microdroplets that are created after breaking and leaving each branch. Furthermore, more control can be applied to the phenomenon of microdroplet breakup. In the numerical study, the ferrofluid microdroplet breakup at different... 

The ongoing Covid-19 pandemic has driven our attention to a simulation of virus dispersion to complete our understanding of airborne transmission. A myriad of studies have shown that respiratory diseases such as MERS, SARS, and COVID-19 can be transmitted by virus-laden droplets released during coughs, sneezing, and normal breathing. To mitigate and prevent the spread of such infectious diseases, investigation of the transmission routes is of great importance. This study has been fueled to harness the CFD tool to simulate the virus-laden droplets dispersion in hospitals inwards. Because of the limitations intertwined with experimental works such as the risk of infection of experimenters, and... 

Liquid-liquid extraction is one of the common chemical processes in the industry which its application is increasing day by day. Taking trend of increase of energy resources, chemical materials and industrial system into account, the necessity use of least energy consumption and material for achieving highest output and purity of products in different industries is attracted researches and industerialists.In this research we have studied the effect of presence of nano particles on both disperses and continuous liquids phases on hydrodynamic of deoplets specially their investigated system in this project was watter, toluene and acetone, and chosen nanoparticles wer carbon nanotubes and TiO2.... 

In general, the output power of the gas turbines decreases as the ambient temperature increases. One of the ways to deal with such a performance loss is to use a wet compression system, which reduces the air temperature rise throughout the compressor. In this system, the water droplets are injected into the compressor inlet and evaporated throughout the stages. As a result, the work of the compressor decreases, and the power and efficiency of the whole engine increase. Most of the researchers in this field have tried to develop mathematical models to investigate the effects of this system on compressor and gas turbine performance in steady-state conditions. However, it is necessary to... 

Emulsions are the intermittent dispersion of liquid droplets that have many applications such as polymerization, dyeing, cosmetics, food industry, etc. Droplets can be created in a variety of ways, but the most important point in emulsification and the greatest efficiency of its applications is when the formed droplets are uniform. In the emulsification process, there is a key parameter called interfacial tension, which affects the behavior of the formed droplets, such as their stability and morphology, and its precise measurement is very effective in the quality control of the mentioned applications. Be. In this research, droplet formation in microfluidic systems due to uniform droplet... 

One way to increase the power and efficiency of the gas turbines is to cool their incoming air. There are different methods to cool down the inlet air. One of the most widely used and suitable method is spraying or fogging the water droplets into the air at the gas turbine air inlet. In this research and for the first time, the effect of fogging system on the performance of a combined cycle incorporated with a J-class gas turbine (M-501J) is investigated using the computational fluid dynamics (CFD). There are so many parameters, which affect the amount of achieved efficiency. A few of them includes the average temperature and humidity at the outlet, the evaporation efficiency of the water... 

In this research, numerical simulation of the impact of a drop on a flat surface with oblique velocity has been performed, using two-phase model of Lattice Boltzmann Method (conservative phase-field). During impact, it is important to investigate two-dimensional drop dynamics and to evaluate the effectiveness of the numerical method used. The model used here restores conservative phase field and preserves mass both locally and globally. In addition, to calculate the slope of the phase field, it calls the center points without engaging finite difference calculations. This makes it efficient for running parallel computations. A fixed dry and hard surface is considered and the drop impacts it... 

Despite the extensive research conducted so far to treat cancer, this disease is still one of the main causes of death worldwide. The results of recent studies reveal the importance of the tumor microenvironment in the growth, proliferation, and invasion of the primary tumor. Most common models in cancer research, such as 2-dimensional in vitro models and xenografts, do not have sufficient ability to mimic the interaction of tumors with human stromal tissue. Therefore, the implementation of 3-dimensional in vitro models with the ability to replicate tumor microenvironments is essential. In this study, a microfluidic platform has been introduced to create parallel models of the tumor... 

The electric field induced response of a charged droplet in an uncharged gel is calculated theoretically. For modeling, the gel is considered as a soft porous solid that is saturated with a Newtonian electrolyte and modeled as a continuum that contains 3 phases: a porous, soft and compressible solid, an incompressible Newtonian fluid and the ions inside fluid. Droplet is modeled as a charged incompressible Newtonian fluid immiscible with the gel. The droplet-gel interface is considered as a surface with electrostatic potential ζ . After obtaining governing equations, they solved by using perturbation methodology and linear superposition. Boundary conditions, especially at the droplet-gel... 

Symmetric T junctions have been used widely in microfluidics to generate equal-sized microdroplets, which are applicable in drug delivery systems. A newly proposed method for generating unequal-size microdroplets at a T junction is investigated theoretically and experimentally. Asymmetric T junctions with branches of identical lengths and different cross-sections are utilized for this aim. A novel equation for the critical breakup of droplets at asymmetric T junctions and one for determining the breakup point of droplets are developed. A good agreement was observed between the theories (novel and previous) and the experiments  

Encompassing an interaction between the phase change material (PCM) and the droplets of a heat transfer fluid, the direct contact (DC) method provides a state-of-the-art solution for the meager melting and solidification rates of PCMs. In the DC procedure, when impinging on the molten PCM pool, droplets evaporate, solidifying the portion of the PCM. For the first time, the impact of single and simultaneous double ethanol droplets, having an average diameter of 2.68 mm, on the molten paraffin wax has been scrutinized exhaustively. Experiments have been carried out through high-speed imaging for various Weber numbers ranging from 179 to 464, pool temperatures from 70 to 95°C, and horizontal...