The paper aims to give a comprehensive investigation of the two dimensional deformation of a single bubble in a straight duct and a 90˚ bend under the zero gravity condition. For this, the two phase flow lattice Boltzmann equation (LBE) model is used. An averaging scheme of boundary condition implementation has been applied and validated. A generalized deformation benchmark has been introduced. By presenting and analyzing the shape of the bubbles moving through the channels, the effects of the all important nondimensional numbers on the bubble deformation are examined thoroughly. It is seen that by increasing the Weber number the rate of the deformation enhances. Besides, because of the velocity dissimilarity between the particles constructing the bubble, the initial coordinates and the diameter of the bubble play a great role in the future behavior of the bubble. The density ratio has a little effect on the shape of the bubble within the assumed range of the density ratio. Moreover, as the Reynolds number or the viscosity ratio is decreased, higher rate of deformation is exhibited. Finally it is found that there is an inverse proportionality between the amplitude and frequency of the bubble deformation.
One of the applications of satellite images is to determine Land Surface Temperature (LST), which has widespread uses in estimation of air temperature (Tair), estimation of vegetation canopy temperature (Tcanopy), investigation of environmental stresses and management options on plant health status and so on. Remotely sensed based LST maps can be generated through different approaches or algorithms; each one fits with a set of input data and climatic conditions and has some advantages and shortcomings. In this study, four LST determination algorithms, namely Mono Window (MW), Improved Mono Window (IMW), Single Channel (SC) and Split Window (SW) algorithms were used to estimate pistachio tree Tcanopy through Landsat 8 OLI/TIRS images and then were evaluated with the aid of ground based measurements in Bahabad region, Yazd province of Iran. The results indicate a substantial difference of about 2.5 degrees Celsius in the average LSTs of different algorithms. Moreover, trend of their differences changes seasonally, emphasizing on importance of LST generation algorithm in warm seasons (regions), compared to cold seasons (regions). Also it was found that LST is a more appropriate parameter than air temperature (Tair) to estimate canopy temperature of pistachio trees (Tcanopy) in the studied area. Under such a condition, Tcanopy determining equations, as a function of LST, have had the error of less than 1 degree Celsius. Furthermore, Split Window algorithm (SW) was found to be more accurate than other LST determining algorithms and substantially, can be recommended for estimation of pistachio canopy temperature, as well.
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