Droplet evaporation coupled with gravity and surface tension on a Wall with the radial Temperature gradients is numerically studied with the arbitrary Lagrangian‒Eulerian method. The influence of the Wall Temperature distribution on the droplet evaporation process, which is less considered in the existing literature, is mainly discussed. The droplet Temperature coefficient of the surface tension and the viscosity on the droplet profile evolution, flow, heat and mass transfer characteristic are also discussed. The results indicate that the droplets become flat first and then retract under the gravity and Marangoni convection during droplet evaporation. There are two high-velocity regions inside the evaporating droplet. One region is at the droplet axis, in which fluid flows to the Wall from the droplet top. The other region is near the droplet surface, where fluid flows to the droplet top. There are turning points on the two sides of which the influence of Wall Temperature distribution on the ratio between the droplet height and the radius of the three-phase contact line (h/Rc), the velocity in the droplet and the surface Temperature converts. All of them are larger before the turning point when the Wall Temperature slope is positive. After the turning point, these are reversed. For both h/Rc and average surface Temperature, there is one turning point, which are t*=1.63×10-4 and t*=1.05×10-4, respectively. For maximum velocity and average velocity in droplet, there are two turning points, which are both t*=1.63×10-4 and t*=1.7×10-5. The droplet morphology changes more obviously when it is with a greater Temperature coefficient of surface tension. Moreover, the turning point is delayed from t*=6.41×10-5 while α is 8 K/m to t*=7.91×10-5 while α is -8 K/m, which indicates that the negative Wall Temperature slope is beneficial to inhibit the Marangoni effect on droplet evaporation.

The analysis of solute and thermal dispersion in pulsatile flow through the stenotic tapered blood vessel is presented. The present problem is an extension of the work done by Ramana et al. who considered the time-invariant arterial Wall. In the present model, the flexible nature of the arterial Wall through the obstruction (called stenosis) is considered and it is achieved with the help of period trigonometric function. In the present study, the impact of the time-dependent arterial Wall on the blood flow dynamics is discussed in details. The rheology of the blood is modeled as a couple stress fluid. The proposed fluid model is the isothermal inclusion of Temperature-sensitive drug coated Titanium dioxide Nano-particles in the couple stress fluid for examining the concentration and Temperature dispersion. The effects of the catheter and permeability of the stenosis are considered in the model. Care has been taken to model the thermo-physical properties of the fluid with the immersed nanoparticle, e. g., TiO2, Ag and Cu. The modeled non-linear and coupled equations are solved by using the Homotopy Perturbation Method. The Temperature and concentration dispersion effects are in the flexible stenotic arterial vessel under the pulsatile physiological pressure gradient are studied and reported in details. The alterations in the axial velocity, resistance to the flow, and Wall shear stress are studied and found out that the high intense vortex regions are identified in the stenotic region. The model has direct applications in the pharmaceutical industry in design and developing the drug to treat stenotic conditions.

It is important to calculate the piston Temperature distribution in order to control the thermal stresses and deformations within acceptable levels. In this study, the SI engine piston heat transfer is calculated and the piston is thermo-mechanically analyzed using finite element method. In order to calculate the heat transfer, a concise resistor model for Wall Temperature prediction is used. For each of the Walls (piston, cylinder and cylinder head), the relevant heat transfer equations simultaneously with two zone combustion model is solved considering three unknown Temperature. The simulations were done by a MATLAB code and the result validated with the experimental data of the EF7.TC engine. The above results have been curve fitted and imported by the commercial ANSYS code to loading the piston.To evaluate properly of results, stress analysis results is compared with real samples of damaged piston and it has been shown that Critical identified areas, match well with areas of failure in the real samples.

Increasing the Temperature of the turbine entrance gases increases the efficiency of the gas turbine cycle. Under these conditions, the combustion chamber Wall Temperature also increases, while there is no high Temperature resistance alloy fitted with air motors. Therefore, it is necessary to use cooling methods to reduce the Wall Temperature. In this study, the cooling effect with compound angles investigated on the combustion chamber Wall Temperature. The three-dimensional combustion chamber k-ɛ is modelled under the conditions of the input speed and the turbulence model in the ANSYS Fluent software. Inlet air is injected from the cooled holes to the mainstream with compound angle, where the cooling flow angle is constant with the 30° horizontally, and the lateral angle changes from Beta =0 up to Beta=60 degrees. The combustion chamber has two flat planes and two sloping plates, in which the arrangement of cooling holes is different. The results show that this method better distributes the cooling air on the Wall surface and covers the space between the cooling holes, especially on flat plates. With this method, the number of cooling holes and the amount of air used to cooling can be reduced.

Longitudinal heat conduction is an important parameter in the cryogenic science, especially in cryogenic heat exchangers. In the present work, the parasitic effect of tube Wall longitudinal heat conduction on Temperature measurement has been studied in cryogenic laminar hydrogen flow. The effects of various parameters such as Wall cold end Temperature, Wall thermal conductivity, gas volumetric flow, and tube Wall thickness have been investigated by finite element method. The model was also validated versus the data obtained from experiments. The simulations showed that Temperature drop occurs in gas flow at the end section of tube length. This section is independent of tube cold end Temperature and leads to large Temperature measurement error in laminar flows. Results showed that a few millimeters change in Temperature sensor position results in measurement errors up to 80 %. The higher tube Wall thermal conductivity and tube Wall thickness result in higher parasitic effects of longitudinal heat conduction.

The effect of radiation on natural convection incompressible viscous fluid near a vertical flat plate with ramped Wall Temperature has been studied. An analytical solution of the governing equation has been obtained by employing Laplace transform technique. It is examined that two different solutions for the fluid velocities, one valid for fluids of Prandtl number(Pr) different from 1+Ra, Ra being the radiation parameter and the other for which the Prandtl number equal to 1+Ra. The variations of velocities and fluid Temperature are presented graphically. Furthermore, the radiative heat transfer on natural convection flow near a ramped plate Temperature has been compared with the flow near a plate with the constant Wall Temperature. It is found that an increase in radiation parameter leads to rise the fluid velocity as well as Temperature.

The aim of this study was to investigate the effect of the thermal condition of furnace Wall and oxidant structure on NOx emission and thermal conditions inside the non-premixed combustion furnace. For this purpose, non-premixed combustion furnace simulations have been performed using OpenFOAM software. Standard k-ε turbulence model, modified eddy dissipation concept combustion model, and discrete ordinates radiation model are used in numerical simulations. In order to analyze the results of numerical simulations, chemical calculations using a well stirred reactor have also been considered. According to the results, increasing the furnace Wall Temperature to reach thermal insulation conditions leads to a significant increase in the average and maximum Temperature inside the combustion chamber and transfers the combustion regime from flameless to high Temperature. In addition, the replacement of carbon dioxide with nitrogen will be accompanied by a decrease in the combustion Temperature due to physical and chemical differences between the two species. According to the results, increasing the Wall Temperature, despite reducing the heat loss, leads to an increase in NOx in the high Temperature combustion regime. The use of carbon dioxide instead of nitrogen in an oxidizer can be considered as a way to reduce heat loss while reducing NOx emission from the non-premixed combustion furnace.