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The collision of droplets on solid surfaces is widely used in oil and gas industry, surface painting, hot surface cooling and spraying of agricultural products. In the present study, the spreading factor of Boger non-Newtonian fluid is experimentally investigated on the dry solid surface such as an acrylic (Plexiglas) and stainless steel sheet and is compared with Newtonian droplets (water and glycerin). The plates of Plexiglas and stainless steel both have a hydrophilic surface. In this research, the Newtonian and non-Newtonian fluids droplets collapse at two heights of 27 and 47 cm from the dry solid surface and are examined in the range of Weber numbers 245≤We≤"538" . The purpose of this study is to investigate the effects of contact velocity on the spreading factor of non-Newtonian and Newtonian droplets during the collision. The results of this study show that with the growth of Weber number (increasing contact velocity), the maximum value and velocity of spreading and receding are increased for the Newtonian or non-Newtonian droplets. Also, with increasing the viscosity of droplets, the value and velocity of spreading and receding are decreased for the Newtonian and non-Newtonian droplets. By increasing the velocity of collision on the Plexiglasas surface (raising the Weber number) up to 32%, the maximum value of droplets spreading is increased 22, 31 and 20 percentage respectively for the fluids of Boger, water and glycerin.

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The impact problems associated with water entry have important applications in various aspects of naval architecture and ocean engineering. Also the calculation of impact force is favorable to many researchers. The purpose of this study is to simulate the impact problem of a wedge into the Newtonian and also Herschel Bulkley dilatant non-Newtonian fluids using the Weakly Compressible Smoothed Particle Hydrodynamics (WCSPH) method. Some non-Newtonian fluids, such as dilatant or Herschel Bulkley dilatant fluids can resist against the wedge entry due to their shear thickening effect. In this research a prediction and correction algorithm is used to solve the governing equations. Density correction and also artificial viscosity (which is used only in Newtonian fluids) are used to prevent the numerical instability. To show the validation, ability and robustness of the generated code to capture the free surface in Newtonian and non-Newtonian fluids, the dam break problem with the image boundary condition is simulated. After validating the code and the used method, the impact problem of a wedge with Monaghan repulsive force boundary condition in Newtonian and Herschel Bulkley Dilatant non-Newtonian fluids are investigated and the results of force, pressure coefficient and velocity of the wedge are presented and compared with experiments and also with each other. To save time, the initial values of hydrostatic pressure are imposed as an initial condition of the fluid.

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Passive micro-mixers have simpler manufacturing in comparison with active micro-mixers and only require energy for flow pumping. In the present study, non-Newtonian fluids and non-Newtonian power-law fluid’s mixing behavior in passive micro-mixers have been studied. Simulation has been performed, using computational fluid dynamics commecrical code of Ansys fluent and two different approaches of two-component mixing have investigated. The first approach studies fluid’s mixing behavior by changing flow behavior index and flow consistency index in 5 different 3D geometries as multiple T-micromixer with aligned and non-aligned inputs in one and two plane, respectively, multiple T-micromixer, double T-micromixer, and T-micromixer, while the second approach studies mixing behavior by changing flow behavior index while flow consistency index is constant in two multiple 3D geometries with non-aligned inputs. In all studies, water was used as Newtonian fluid and carboxymethyl cellulose solution was used as non-Newtonian fluid. The studied range of Reynolds number was 1 to 100. In both approaches, the results for mixing index and pressure drop for power-law index according to criterion are reverse of each other; it means that in the first approach, with increasing power-law index, the mixing index increased and the pressure drop decreased and in second approach, this procedure is reversed. But, procedure of non-dimensional fully developed velocities in two approaches investigated is similar in comparison to geometries with non-aligned inputs.

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The coastal waves caused by landslide in the lake of reservoir dams can threaten the safety of the dam. Therefore, the exact recognition of hydraulic flow due to coastal waves has always been of interest to researchers. So far, extensive laboratory and numerical research has been devoted to it. Also, the phenomenon of landslide in the lake of dams and rivers, and the production and propagation of waves resulting from it, is one of the most important and complex issues in the field of hydraulic engineering. Today, the expansion of numerical relations and the modeling process have somewhat contributed to a rational understanding of these phenomena. In this research, a Lagrangian method is used for solving governing equations. Initially, the hydrodynamic method is defined as an explicit three-step incompressible smoothed particle hydrodynamic. This method, by replacing the fluid with a set of particles, provides an approximate solution to the fluid dynamics equations. In this simulation, there are a series of arbitrary interpolation points that can be assumed to be fluid particles. All variables are calculated by these points and are calculated by an interpolation function. In order to validate the method, the dam break problem on dry bed and the subsurface landslide problem have been used. In the first issue, the correlation coefficient of 0.9998, the mean absolute error of 0.5426 and the efficiency coefficient of the Nash-Sutcliff model 0.974 for the calculated parameters indicate that the model is accurately calibrated, which demonstrates the high capability of this method in simulating free surface fluids and wave-related phenomena. Also, comparing the measured results with the experimental data in the sub-surface landslide simulation showed that the correlation and mean square error correlation coefficients were 0.95 and 0.0071 respectively, which indicates the high accuracy of the model in calculating the water surface profile caused by landslide subsurface. The results showed that at times after 2 seconds, numerical waves tended to release more than its experimental state, with a difference between the ranges of 5 to 10 cm. This is due to the turbulence of the free surface of water causing the flow of complexity. For smaller body weights and deeper depths of submergence, these differences will be lower in scope.
Then three landslide modeling scenarios were designed and implemented. In this study, slopes and non-rigid bodies were considered as a rheological material (pseudoplastic fluid) and entered into modeling as Carreau Yasuda non-Newtonian fluid. The results were reported at 0.3 and 0.6 seconds, and then they were analyzed.
The innovation aspect of this research is that the study of non-rigid slopes during landslide and falling and sliding of non-rigid bodies on them, as well as the production and propagation of waves from it, have not been investigated so far. The purpose of this paper is simulation and review it by an explicit three-step incompressible smoothed particle hydrodynamic. On the other hand, the choice of non-Newtonian Carreau Yasuda fluid to simulate the slope and non-rigid body is another aspect of the innovation of the present study.

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Investigating dense flows containing cohesive sediments (turbidity currents) in water environment has been a main interest for researchers in hydraulic and fluid mechanic science. This kind of flow streams at bed surface because of higher density than water and penetrate to overhead water, which causes turbidness.  In the following research, this kind of flow has been modeled using two-phase simulation with smoothed particle hydrodynamics Lagrangian method. A SPHysics2D code has been developed for modeling, in which pressure value is explicitly calculated using equation of state. Also, Herschel-Bulkley-Papanastasiou single relation non-Newtonian viscoplastic model has been used for modeling cohesive sediment phase. After that for investigating the amount of penetration of cohesive sediment mixture in limpid water, advection-diffusion equation was used for developing code. Finally, one and two phase results obtained from the present model were compared to experimental models. The study shows that the present developed model is able to model these flows desirably and could be utilized for studying concentration amount, dense flow penetration and their propagation in water environment.

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In this paper, an asymmetric breakup of non-Newtonian droplet (with power law behavior) in a new geometry (network junction) has been investigated. The geometry can break an initial droplet into six unequal size droplets. The research method is numerical simulation with Volume of Fluid (VOF) algorithm. The numerical results are compared with the results of a benchmark problem and a very good agreement is seen. The results showed that in areas close to the wall, mixing of materials of inside droplet is performed better, which is important in industrial applications of droplet based flows, especially in pharmaceutical and chemical industries. The results showed that the maximum vorticity magnitude in the K1 branch (the lowest output branch in the system) is 26, 44 and 28 % more than the maximum vorticity magnitude of the branches of K2, K3 and K4 (K4 is the highest output branch is in system). Also, maximum effective viscosity in the K1 branch is 27, 29 and 24 % less than the maximum effective viscosity in the K2, K3 and K4 branches, respectively. Therefore, K1 branch has the best performance in mixing of the material of inside droplet among the output branches. It was also revealed that the pressure of inside of droplet (both before and after breakup) is constant along the channel width.