Solutions for mean normal velocity and temperature show the transition from the nearly collision-free regime to the Navier-Stokes-Fourier regime, which is characterized by a boundary lay[r]

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In addition, the study of thermal radiation also included in this research. According to Anbuchezhian et al. (2012), radiation comes from solar energy, and the resultant solar energized resources, such as wave power, wind, biomass, and hydroelectricity, all give an explanation for most of the accessible renewable energy that is present on the Earth. Meanwhile, thermal radiation refers to electromagnetic radiation **generated** by the thermal motion of charged particles in matter. It consists of ultraviolet rays, infra-red and light rays follows a nuclear explosion. The examples of major radiation exposure in real live events are Hiroshima and Nagasaki, Three

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industrial application use impinging jets, due to their higher convective heat transfer coefficient values. Here, the researchers stated that there was less available information regarding an increase in the heat transfer rates, when twin impingement jets were placed horizontally, at a distance from the stagnation point. Some studies made use of a twin impingement jet process for numerically and experimentally increasing the heat transfer values. In this study, the researchers carried out a numerical simulation that was based on an RNG k-ε turbulence model, in order to determine the cooling process for the **heated** surface of an aluminium **plate**. For this purpose, they used a Twin Jet Impingement Mechanism (TJIM), which consisted of 9 models. Furthermore, they also studied the effects of the nozzle-nozzle distances, nozzle-**plate** distances and Re number of the convection heat transfer for calculating the heat transfer coefficient, Nu number and a thermal enhancement factor. Some of the main conclusions observed in the simulation study were further used for validating all the experimental results and determining all major parameters that could affect the heat transfer rate, Nu number and distribution of the static pressure. The arrangements of all jets showed that Model 1 was ideal for calculating the Nu number when S/D= H/D=0.5. Meanwhile, Model 9 displayed the worst results, where S/D= 1.5 and H/D= 5.5. The results also showed that an irregular distribution of a local Nu number (Nu) on the impinged surface occurred due to a decrease or increase of the **flow** turbulence. Various twin jet arrangements showed that Model 9 displayed the worst results, where S/D= 1.5 and H/D= 5.5. All numerical results were validated after comparing the simulation and experimental results for the TJIM. This further described the temperature distribution on a **flat** metal surface for different models. Here, the researchers have calculated the enhancement factor using different nozzle arrangements in 9 models. This value ranged from 6.4% and 24.3%, in the case of simulation studies, whereas in the actual experiments, it ranged from 5.3% to 37.9%. The simulation model showed a 12-41% increase in the average heat transfer rate for the complete aluminium **plate**. Based on the validation model, the experimental and numerical tests

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gold, iron and or their oxides like titanium. Moreover, it is well known that the heat transfer properties of the conventional base fluids such as water; mineral oil and ethylene glycol are very poor compared to that of most solids. A comprehensive survey of convective transport in nanofluids was presented by Buongiorno [3]. He reported that a satisfactory explanation for the abnormal increase in the thermal conductivity and viscosity of nanofluids was yet to be found. Li and Xuan [4] experimentally investigated the various transport properties of nanofluids. Kuznetsov and Nield [5] examined the influence of nanoparticles on the natural convection boundary-layer **flow** past a vertical **plate**. Thereafter, several researchers [6-9] have investigated convention flows of nanofluids under various physical conditions. Ahmad et al. [10] extended the well known Blasius and Sakiadis boundary layer **flow** problems to include the nanofluids. Makinde and Aziz [11] presented a similarity solution for boundary layer flows of nanofluids over a convectively **heated** stretching sheet. The effects of thermal radiation and viscous dissipation on boundary layer **flow** of nanofluids over a permeable moving **flat** **plate** were reported by Motsumi and Makinde [12]. Recently, the influence of magnetic field on the boundary layer **flow** of electrically conducting nanofluids was investigated in some studies [13, 14]. However, in their theoretical analysis, the complex interaction of the nanoparticles electrical conductivities with that of conventional base fluids was ignored. In reality, the electrical conductivities of nanoparticles are not equal to that of conventional base fluid and therefore cannot be ignored in order to obtain a realistic solution to the problem.

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In this paper the laminar **flow** of Newtonian conducting fluid produced by a moving **plate** in presence of transverse magnetic field is investigated. The basic equation governing the motion of such **flow** is expressed in non-dimensional form. Analytic solution of the governing equation is obtained by Laplace transformation. Numerical solution of the dimensionless equation is also ob- tained with the help of Crank-Nicholson implicit scheme. Velocity profiles of the corresponding problem are shown in the graphs.

Dyer J.R. [1] in this paper author used the concept of a theoretical and experimental study of laminar natural- convective **flow** in **heated** vertical duct. The ducts are open ended and circular in cross section and their internal surfaces dissipate heat uniformly. Temperature and velocity fields and the relationship between Nusselt and Rayleigh numbers were obtained by solving the governing equations by step-by-step numerical technique. Two Rayleigh numbers are introduced expressing in terms of the uniform heat flux and the other in terms of the mean wall temperature. The effect of the prandlt number on the relationship between the Nusselt and Rayleigh numbers is discussed. Three inlet conditions were examined they all gave the same Nusselt relationship at small Rayleigh numbers. It is also observed that the difference between the Nusselt numbers obtained at large Rayleigh number were only small. Experimentally determined Nusselt numbers with air as the convicted fluid, agreed satisfactorily with the theoretical relationship.

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range of angles of attack [9]. This discrepancy in results may be due to the fact that the earlier work was done on finite airfoils. This also indicates that spanwise **flow** has been affected by the leading edge protuberances. Johari et al. [10] experimentally studied the role of sinusoidal protuberances on the leading edge of a two-dimensional airfoil and observed that the amplitude of the protuber- ances plays a more significant role on the performance than their wavelength. They also found from **flow** visua- lization that the **flow** separation occurs earlier in the re- gion between two protuberances [10]. Force measure- ment tests [9-12] at low Reynolds number on nominally two-dimensional airfoils demonstrated gradual stall with greater post stall lift for modified model compared to unmodified one. However, the pre stall performance for both modified and unmodified models was more or less the same. It can be concluded that the tubercles have li- mitation to be used in bounded airfoils, that is, for cases which can be considered as infinite two-dimensional air- foils [10,12-14].

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In this thesis we will be applying a simple no-slip condition at the moving contact point or line, which is the common interface between the air-water and the solid boundary. As the solid boundary moves downwards into the water, say, it is expected that in reality the contact point will move relative to the solid boundary, but here we keep to the no-slip case as a prime one to be explored. It is worth mentioning some of the many other aspects of moving contact points nevertheless. Some general problems relevant to the ship side analysis and the behaviour of the air-water interface near the contact line may be found in Foda & Cox (1980), King (1991), Vanden-Broeck & Tuck (1994), Billingham & King (1995), King et al. (1998), and more recently in Somalinga & Bose (2000). The study of Foda & Cox examines the spreading on a water-air interface of a thin liquid film for the situation in which surface tension gradients drive the motion. (Such capillary effects are excluded from consideration in the work of the present thesis but are still of much interest, for example see the recent paper of Kang & Vanden-Broeck 2000). King investigates the moving contact lines in slender fluid wedges. He finds the asymptotic and numerical solutions for a novel two-point boundary-value problem and the displacement of the contact point. Vanden-Broeck & Tuck investigate the **flow** near the intersection of the free surface with a vertical wall. The free surface here typically makes an angle of 120° with the wall and it is assumed that the velocity close to separation is small. A nontrivial local solution with 90° and 180° contact angles is also computed here by a series truncation. Billingham and King (1995) analyse computationally and analytically the problem of a **flat** **plate** penetrating an air-water interface for both small and large times using the boundary integral method. It is found that far-field capillary waves are **generated** when the contact angle is close to 90° and, as time increases, the interface becomes more non-linearly deformed. King et al. (1998) perform an extension of the same method to the case of an inclined **plate**/interface system. Similar profiles are again found. Somalinga and Bose (2000) investigate, using finite elements, the development of the free surface located between a static wall and a rod entering the fluid in a dynamic wetting process. General profiles are predicted for displacement and velocity fields for a numerical mesh which appears to be relatively coarse.

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Boundary layer of natural convection **flow** has extensively been studied for long years. Many experimental and theoretical investigations have been carried out to study the behaviour of the development of boundary layer **flow** on various geometries, for instance, cylinder, sphere and **flat** **plate** with different boundary conditions. In fact, the natural convection on a vertical **plate** has received more attention because the phenomenon of free convection is employed in many engineering applications, for example, cooling industrial equipments or circuit boards in electric models. Moreover, the major applications of free convection link with solar energy systems, for example, natural ventilation uses natural convection to supply different building with fresh air. Simon [1] performed numerical simulations to study laminar natural convection **flow** on an isothermal vertical

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Change in **flow** rate owing to amendment (increase) within the pure mathematics of a pipe system i.e., amendment (increase) in crosswise sets up eddies within the **flow**. This eddies doesn't follow a straight path to the middle it follows a volute, whirling path. This path is named a vortex. A characteristic feature of a vortex is that the skin of the vortex moves slowly and therefore the centre moves quickly. If the crosswise of a pipe with fluid flowing through itis **suddenly** enlarged at sure place, fluid rising from the smaller pipe is unable to follow the abrupt deviation of the boundary. Then the contour takes a typical radiating pattern. This creates pockets of turbulent eddies within the corners leading to the dissipation of energy into building block energy. and therefore the fluid flows against associate degree adverse pressure gradient. The upstream pressure p1 is below the downstream pressure p2since the upstream rate V1 is over the downstream rate V2 as a consequence of continuity. The fluid particles close to the wall owing to their low K.E. cannot overcome the adverse pressure hill within the direction of **flow** and thus follow up the reverse path underneath the favorable pressure gradient (from p2 to p1). This creates a zone of re-circulating **flow** with turbulent eddies close to the wall of the larger tube at the abrupt amendment of crosswise, leading to a loss of total energy.

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The study of heat transfer analysis is an interesting research area due to its potential applications in engineering, such as nuclear plants, combustion modeling, heat exchangers, cooling systems design, various propulsion devices for air craft’s, chemical engineering and electronics etc. Moreover, heat transfer by thermal radiation plays a significant role on the heat transfer characteristics where high temperature is occurred. Furthermore, the **flow** field is influenced noticeably with the effect of magnetic field. Considering its wide applications in science and engineering, a large number of theoretical, numerical and experimental works have been conducted by many investigators. Pop and Na [1] developed a mathematical model in free convection **flow** for arbitrary inclined **flat** **plate** embedded in a porous medium to analyze the behavior of the **flow** and heat transfer characteristics. The effects of conduction-radiation on natural convection boundary layer **flow** of viscous incompressible fluid over an isothermal horizontal **plate** studied by Hossain and Takhar [2]. Hossain et al. [3] analyzed the effect of radiation on natural convection **flow** in incompressible fluid along a uniformly **heated** vertical **plate**. Abdel-Naby et al. [4] investigated radiation effects on MHD unsteady free convection **flow** over a vertical **plate** with variable surface temperature. Ali et al. [5] employed the implicit finite difference method to analyze the effect of radiation and viscous dissipation on conjugate free

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number that measures the rarefaction of any gas molecules and represents the ratio between the mean free path λ to a characteristic length L). For this purpose, we utilize coupled systems of non-stationary BGK kinetic equations, one for each component of the neutral gas. The radiation force effect is inserted into the force term of the Boltzmann kinetic equation. These procedures are done by applying the Liu-Lees model for two-side Maxwell non-equilibrium distribution functions using the moment method. Moreover, the manner of the macroscopic characteristics of the non-homogenous gas is estimated for different radiation force strength according to different fixed, rigid **plate** temperatures. The temperature and concentration are, in turn, substituted into the related non- equilibrium distribution function. This approach permits us to investigate the manner of the equilibrium, non- equilibrium, and non-stationary distribution functions for different magnitudes of the molar fraction parameters. Also, the remarkable non-equilibrium thermodynamic characteristics of the entire system (neutral non- homogenous gas + **heated** plane solid **plate**) are calculated. Especially thermodynamic forces, entropy, entropy generation, entropy flux, and kinetic coefficients are investigated. Furthermore, the consistency of thermodynamics second law, Boltzmann H-theorem, and Onsager's relation are illustrated. The ratios among the different participations of the internal energy alteration are estimated via the Gibbs' formula. The results are applying to the argon-helium neutral non-homogenous gas. Finally, the remarkable conclusions of the paper are indicated.

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(2018) Flow structure generated by laser-induced blast wave propagation through the boundary layer of a flat plate.. Aerospace Science and Technology, 78, pp.[r]

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Abstract: Two dimensional free convection and mass transfer **flow** of an incompressible, viscous and electrically conducting fluid past a continuously moving vertical **flat** **plate** in the presence of heat source, thermal diffusion, large suction and under the influence of uniform magnetic field applied normal to the **flow** is studied numerically. In this research work we make the governing equations dimensionless by appropriate co- ordinate transformation. We also consider the effect of heat source parameter and soret number for the above mentioned problem. Then these dimensionless momentum, energy and concentration equations are solved numerically by using explicit finite difference technique with the help of a computer programming language Compaq Visual Fortran 6.6. The obtained results of this study have been discussed for the different values of the well know parameters with different time step. The results are discussed in detailed with the help of graphs and tables to observe the effect of different parameters.

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The sudden deceleration of the human head during accidents which occurs on the car bonnet (Figure 6.13) is seen to be a large cause of permanent injury and death. This observation is applied from a current study being undertaken by a fellow research student who is currently investigating this phenomenon. Thus it is seen that using the free **plate** is greatly advantageous in this instance. Though it is not physically possible to have a **plate** that rests freely on the bonnet it is possible to have the **plate** constrained by fixtures that allow movement, seen in Figure 6.14. There is also the consideration of when the bonnet reaches the engine block which is also a point where severe injury can occur. The possibility of raising the bonnet higher would be an alternative but would conflict with current aesthetics in car design. The use of

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Abstract In this study **flat** **plate** structures designed only for gravity load were retrofitted against earthquake load using various methods and their seismic performances were evaluated to verify the effect of the seismic retrofit. Both the element level retrofit scheme such as column jacketing and the system level scheme such as installing steel braces between columns were employed. The nonlinear static and dynamic analysis results showed that both strength and stiffness were enhanced as a result of the seismic retrofit. Among the retrofit schemes steel braces were most effective in increasing stiffness as well as strength, and the effectiveness depended on the size of additional steel columns connected to the braces. Also the effect of column jacketing was significantly increased when the critical section of column-slab connection was reinforced by steel **plate**.

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If one wants to be more accurate in a measurement with the Pitot tube, some details should be taken into consideration. The pressure difference between the static pressure and stagnation pressure is determined with two different Pitot tubes which are not on the same streamline and Bernoulli’s equation does not hold. Moreover, the static pressure below the **plate** was found to be not identical to the static pressure measured with the Pitot tube in the wind tunnel. Therefore a more accurate method would be to place the Pitot tubes on the same streamline as much as possible or a Pitot tube should be designed which can measure the stagnation and static pressure in the boundary layer. 15.2 The Hot Wire Measurement

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Among the phenomena that occur as a result of contact between two surfaces is friction sound, in which surface roughness is of great importance. In this study, the parameter of contact stiffness is used to explain the frequency characteristic of vibration **generated** by the rubbing of **flat** surfaces under a small load. A 3-disk configuration rubbing method was used, which provides a unique characteristic of the system's frequency response function containing specific information about the rubbing vibrations. It is shown that the peak frequency of the rubbing vibration can be explained by using a two-degrees-of-freedom model incorporating the parameter of contact stiffness. A quantitative relationship between the surface roughness and the peak frequency of the rubbing vibrations was established.

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Jet impingement is an attractive cooling mechanism because of its higher heat transfer rate of cooling. Because of this, jet impingement has been widely used in many industrial applications. Impingement of air jet to study the heat transfer rate is a new development for cooling in industry. Jet impingement method is the least expensive method to achieve the desired results. Due to this more prior research has been given to understand the heat transfer characteristics. Cooling of electronic equipment is helpful in computer chip. Computer chip will generate much heat. Due to this, jet impingement has been developed in recent years. Jet impingement gives higher heat transfer rate over a small area so it is widely used in different industrial applications but it gives high heat transfer rate for a short **flow** path. In this air is used as medium for cooling. Many researchers investigated fluid **flow** and heat transfer characteristics by impinging jet on smooth and **flat** surface.Few industrial processes which employ impinging jets are drying of food products, textiles, films and papers; processing of some metals and glass, cooling of gas turbine blades and outer wall of the combustion chamber, cooling of electronic equipment’s etc.

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