Simulation of Agricultural Wetland Area of Typology C through The Van Genuchten Model Approach

The use of groundwater flow equations in porous media is often applied optionally, i.e. under saturated soil or only for unsaturated conditions. Tidal agricultural zone of typology C, is an example of how these two assumptions can occur simultaneously. The parameters of the hydraulic conductivity values in this zone can be illustrated by Van Genuhten model approach so that the distribution of water content in spatiotemporal can be described precisely. The numerical model used in land wetting simulation is a finite different method of up to 1D horizontally with an explicit scheme. In the context of the managerial aspects of water management, the scheduling system of tidal-lowland for agricultural purposes, will also be explained from the simulation results.

Elastohydrodynamic Lubrication in Ball Thrust Bearing

This paper presents the theoretical characteristics of elastohydrodynamic lubrication (EHL) in point contact under steady operating conditions of ball bearing thrust bearing. The numerical simulations employed a finite different method, Newton Raphson method and multigrid method to solve the modified Reynolds equation with a Non-Newtonian fluid. The general numerical schemes are implemented to investigate the profile of pressure and film thickness, with varying applied loads viscosity of lubricants and speeds. The results show that the applied load has significant effect on the film thickness profile. The contact is increase area but film thickness decrease as the applied load increase. The minimum film thickness and friction coefficient both increase significantly as viscosity of lubricant is increased. The increasing of surface velocity, the film thickness increase but film pressure decrease.

Model Numerik 1D Penggerusan Endapan di Mulut Muara dengan Metode Beda Hingga

Sedimentation at estuary river have potency to cause floods because the narrowing of estuary as outlet. Sedimentation process can be caused by the so small river discharge at dry season so that cannot to flushing the sediment that happened at estuary mouth. When the rains arrive, river discharge which starting to big shall no long castaway to sea freely, so that causes floods in headwaters. Numerical simulation by using finite different method with Preissmann implicit scheme conducted to see ability of river discharge in early the rains to flushing the sediment in estuary mouth. Simulation was done at river with sediment elevation at + 4.00 m in estuary mouth. Boundary condition in the form of discharge hydrograph in early the rains at upstream boundary and also critical water surface elevation in sediment top and sea level at downstream boundary applied at model to see behavior of sediment transport and change of profile at bottom channel that happened. Simulation result show with 24 hours floods charge in early the rains, sediment volume of flushed equal to 20,52 %, with elevation reside at + 3,179 m. Sediment will fully under sea-water face after 9 days simulation. Change of upriver discharge and tidal elevation at downstream will influence to speed of stream that happened. By the end of simulation, the bottom profile of channel influenced of tide.

Effect of Solid Particle on Rough Thermo-Elastohydrodynamic Lubrication with Non-Newtonian Lubricant

This paper presents the performance characteristics of rough thermo-elastohydrodynamic lubrication (TEHL) with non-Newtonian liquid–solid lubricant based on a Power law viscosity model. The time independent modified Reynolds equation, elasticity equation and energy equation were solved numerically using finite different method, Newton-Raphson method and multigrid multilevel methods were used to obtain the film pressure profiles and film thickness in the contact region. The effects of amplitude of surface roughness and concentration of solid particles are examined. The simulation results showed surface roughness has rapidly effect on film pressure and film temperature. The effect of solid particle can be increases film thickness and decreases friction coefficient.

Theoretical Investigation of Transient Lubrication in Spur Gear

This paper presents performance characteristics of transient thermo-elastohydrodynamic lubrication (TEHL) in line contact with Newtonian fluids. The time-dependent modified Reynolds equation, energy equation and elasticity equation with initial conditions were solved numerically using finite different method, Newton-Raphson method and multigrid multilevel method for an involutes spur gear to obtain the film pressure profiles, film thickness profiles, film temperature and friction coefficient in the contact region. In this analysis, the load is applied on either two pairs or one pair of gear teeth. The simulation results show that at approach point, the film thickness is minimized and film temperature rapidly increases. Film temperature and friction coefficient were suddenly increase when the transition from two pairs to one pair and vice versa are modeled as a step variation of load. The friction coefficient and film temperature were occurrence at pitch point. Film temperature and friction coefficient increase but film thickness decreases when applied load increases. For increasing of speeds, film thickness and film temperature increase but friction coefficient decreses.

Transient Thermo-Elastohydrodynamic Lubrication of Rough Surface in Soft Material

This paper presents the effects of transient rough surface thermo-elastohydrodynamic lubrication (TEHL) of rollers for soft material with non-Newtonian fluid base on power law model. The time independent modified Reynolds equation, energy equation and elasticity equation were solved numerically using finite different method, Newton-Raphson method and multigrid multilevel method to obtain the film pressure profiles, film thickness profiles and friction coefficient in the contact region. The simulation results show surface roughness has effect on film thickness but its effect on film temperature is insignificant. The minimum film thickness decreases while the coefficient increases when the amplitude of surface roughness increases. Meanwhile, increasing applied loads causes the friction coefficient to decrease.

HEATING EFFECT OF THERMALLY SIGNIFICANT BLOOD VESSELS IN PERFUSED TUMOR TISSUE DURING CRYOSURGERY

The purpose of this work is to evaluate the heating effect of thermally significant blood vessels (TSBVs) during cryosurgery process. A theoretical model is developed to describe the heat transfer of perfused tissue containing a 6 mm-radius tumor and a countercurrent artery–vein pair in the vicinity of the tumor. The novelty of the model is that both the Pennes bio-heat transfer equation and the energy transport equation are used to govern the heat transfer of perfused tumor tissue and the heat convection and diffusion of the blood flow. The explicit finite different method is used to solve the transient equations with the second boundary condition set for the boundary of both the blood vessels and the tissue. The results indicate that the heating effect of the blood on the tissue surrounding the countercurrent artery–vein pair may cause parts of the tumor to be insufficiently frozen for a pre-designed cryosurgery protocols, and which may lead to regeneration of the tumor cells. A quite important issue has been raised by this study, i.e., the cryosurgery protocols should be carefully designed with full attention being paid to the heating effect of TSBVs in case of a countercurrent artery–vein pair in the vicinity of the tumor.

Simulation Flows Over Hemisphere at the Bed of an Open Channel by DNS and Immersed Boundary Method

The immediate aim of this study is to check the accuracy of Kajishima’s method (one kind of immersed boundary method) for the direct numerical simulation (DNS) of turbulent channel flow over a complicated bed. In this paper, the simulation of three dimensional, time -dependent turbulent flows over a fixed hemisphere at the bed of an open channel is carried out. A finite different method (FDM) is applied with a staggered Cartesian mesh. The forces, the moments about the center of the hemisphere, and the distribution of pressure on the hemisphere in the plane of symmetry are calculated.