Contact line dynamics and deposition pattern of a colloidal drop are strong functions of the particle wettability.

Micropattern-controlled two-stage wicking dynamics dictate the enhancement of wicking in hierarchical micro/nanostructured surfaces over bare microstructures.

Abstract-S mart Parking S ystems obtain information about available parking spaces, process it and then place the car at a certain position. A prototype of the parking assistance system based on the proposed architecture was constructed here. The adopted hardware, software, and implementation solutions in this prototype construction are described in this paper. The effective circular design is introduced here having rack-pinion special mechanism which is used to lift and place the car in the certain position . The design of rack pinion mechanism is also simulated using AUTODES K INVENTOR and COMS OL software.

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Inkjet printing of biopolymer droplets is gaining popularity because of its potential applications in regenerative medicine, particularly the fabrication of tissue-regenerative scaffolds. The quality of bioprinting, which affects cellular behaviors and the subsequent tissue formation, is determined by the solvent evaporation and deposition processes of biopolymer droplets, during which instantaneous local viscosity and surface tension changes occur because of the redistribution of the biopolymer inside the drop. Such dynamics is complex and not well understood. Most biopolymer inks also contain multiple solvents of distinct evaporation rates, further complicating the system dynamics. Using high-speed interferometry, we directly observe in real time the instantaneous drop shape of inkjetprinted picoliter gelatin drops containing glycerol and water. It is observed that, for bisolvent gelatin drops with surfactants, highly viscous gelatin and glycerol accumulated near the pinned contact line at an early stage suppress the evaporation-driven outward flow and create a stagnation zone near the contact line region. Lower surface tension at the contact line, because of its high local surfactant concentration, as compared to the drop apex induces a strong Marangoni recirculation, which in conjunction with a stagnation zone in the contact line region causes the instantaneous drop shape to transition from a spherical cap to a volcano shape during evaporation and resulting in a volcano-like deposition profile. In contrast, the suppressed evaporation outward flow together with a weak Marangoni flow leads to a domelike deposition for the case without surfactant. The role of surfactant in polymer drop deposition with water-only solvent is also investigated and compared against that of bisolvent drops. For the single-solvent case, the deposition profile is found to shift from a coffee-eye shape in the presence of surfactant to a uniform deposition without surfactant. The results reveal new insight into the complex role surfactant plays during polymer drop evaporation and deposition processes.

Understanding the temperature profile across a liquid–vapor interface in the presence of phase change is essential for the accurate prediction of evaporation, boiling, and condensation. It has been shown experimentally, from non-equilibrium thermodynamics and using molecular dynamics simulations, the existence of an inverted temperature profile across an evaporating liquid–vapor interface, where the vapor-side interface temperature observes the lowest value and the vapor temperature increases away from the interface, opposite to the direction of heat flow. It is worth noting, however, that an inverted temperature profile is not always the case from other experiments and simulations. In this study, we apply non-equilibrium molecular dynamics simulations to systematically study the temperature profile across a liquid–vapor interface during phase change under various heat fluxes in a two-interface setting consisting of both an evaporating and a condensing interface. The calculated vapor temperature shows different characteristics inside the Knudsen layer and in the bulk vapor. In addition, both the direction and magnitude of the vapor temperature gradient, as well as the temperature jump at the liquid–vapor interface, are functions of the applied heat flux. The interfacial entropy generation rate calculated from the vibrational density of state of the interfacial liquid and vapor molecules shows a positive production during evaporation, and the results qualitatively agree with the predictions from non-equilibrium thermodynamics.

Air film evolution underneath a drop impacting on a surface can cause the drop to either bounce off or make contact. Water drops impacting on a dry surface exhibited a transition from bouncing to the kink and film modes of contact. Additionally, a dimple mode of contact was observed on a lubricated, smooth surface. Here, we report experimental findings of drops impacting on a lubricated, smooth surface under both reduced and atmospheric pressures using liquids of two different viscosities. The kink mode observed on a dry surface only occurs at low impact velocities under reduced pressures but is completely absent at the atmospheric pressure on a lubricated surface. The horizontal extent of the dimple agrees well with the incompressible and compressible scaling within the inertial regime. The experimentally measured horizontal extent of the kink shows good agreement with the existing theoretical scaling. Slight deviations in the contact mode transition were observed between experiments and previously reported simulations, presumably due to the velocity slip at the air–lubricant interface in the present study.