Constant Fluid Properties Research Articles

Influences of Newtonian heating and Darcy's law in micropolar fluid flow over a magnetized stretchable disk: A Bayesian analysis

A laminar two-dimensional magnetized micropolar fluid flow passed through a stretchable surface is examined. The axi-symmetric time-independent thermal flow experienced the impacts of Darcy's law, thermal conductivity, and Newtonian heating. The dimensionalized flow model is governed by similarity transformations. The resulting non-linear flow system is numerically solved through Runge-Kutta-Fehlberg (RKF-45) built in scheme. The graphics illustration of velocity and thermal fields for multiple physical parameters is presented. The numerical values at the disk surface for couple stresses, thermal rate, and shear stresses are also calculated. A Bayesian approach is used to assess the association degree amongst the under-study constraints and variables. The magnitude of the microrotational profiles is enhanced by the combined effect of micropolar parameters while an opposite effect is observed in microrotational field against magnetic and porosity parameters. The temperature field is modified through enhancing values of conjugate parameters. Moreover, such thermal field is larger for variable thermal conductivity as assumed to constant fluid property.

Assessment of Bödewadt flow over a stretchable porous surface with variable physical properties: A comparative study

Rotating flows occurring over stationary or revolving boundaries have widespread applications in engineering related processes including electrochemistry, turbomachinery (because it involves turbines), compressors and centrifugal pumps, rheometers etc. and in food and chemical processing industries. Bödewadt flow situation concerns a laminar three-dimensional motion taking place over a planar surface in a viscous fluid which is in a state of rigid body rotation at the far field. Present research applies two distinct viscosity-temperature relations to analyze the Bödewadt flow over a stretching porous surface. . A user friendly and robust computational tool bvp4c of MATLAB is utilized to inspect the behaviors of controlling parameters on the resulting boundary layer formations. Interestingly, results corresponding to the two variable viscosity models in case of water are close to each other. The results indicate that either sufficient wall permeability or sufficient surface stretch rate is necessary to have a meaningful solution for the temperature profile. In the case of variable properties, computational data for the drag exhibited at the disk substantially differs from that found for the case of constant fluid properties.

Thermal‒hydraulic‒mechanical‒chemical coupling analysis of enhanced geothermal systems based on an embedded discrete fracture model

Enhanced geothermal system (EGS) is subject to the comprehensive effects of multiple physical fields during the long-term heat extraction process, including hydraulic (H), thermal (T), mechanical (M) and chemical (C) fields. The embedded discrete fracture model (EDFM) can effectively simulate the variations of flow, temperature, mechanical and concentration fields in fractured reservoirs. At present, however, the thermo-hydro-mechanical-chemical (THMC) coupling model based on EDFM is less researched. In this paper, the THMC coupling model of fractured reservoir is established based on EDFM by considering the changes in reservoir heterogeneity and physical properties as well as water–rock reactions. Then, the spatiotemporal evolution of flow, temperature, displacement and concentration fields in the operation process of EGS is simulated and analyzed. And the following research results are obtained. First, when the permeability of the basement rock is low, the production temperature decrease during exploitation is gradual, allowing EGS to maintain a high exploitation temperature for an extended period. However, lower permeability may result in a decrease in the quality flow rate from production wells, thereby affecting net heat extraction power. Second, when fracture permeability or fracture opening changes, EGS can output higher temperature stably for a certain period and then the temperature decreases at different amplitudes. When the fracture permeability increases to a certain value or the fracture opening decreases to a certain value, the influence of the change in fracture parameters on production temperature gets weak. Third, After 40 years of EGS operation, considering variable property fluids results in a 22 °C lower exploitation temperature compared to using constant property fluids, and considering water–rock reactions results in a 15 °C lower exploitation temperature, with a 12.5 % increase in reservoir average porosity. In conclusion, when researching a long-term operating EGS, it is necessary to comprehensively consider the influences of reservoir rock parameters, physical properties of injected fluid, water–rock reaction and other factors. And in the future, attention shall be paid to the two-way coupling of chemical reaction and mechanical deformation of other mineral compositions in the reservoir to the hydro-thermo-chemical field influence, so as to provide more accurate and reliable prediction for the engineering development and utilization of EGS reservoirs.

Modulation of Turbulence Flux Budgets by Varying Fluid Properties in Heated High Prandtl Number Flow

The accurate computational modelling of momentum and heat transfer in turbulent wall-bounded flow is still a challenging task, especially for fluids with high molecular Prandtl numbers. Due to the steep temperature gradients, the strong variation of fluid properties becomes an additional important issue. The present Direct Numerical Simulation study specially addresses this problem considering a representative working fluid in terms of a real heat transfer oil with temperature-dependent material properties. Near the heated wall, the increase in molecular viscosity significantly attenuates the turbulent convective fluxes of both momentum and heat, despite the markedly increased enthalpy fluctuations. As the thermal conductivity decreases markedly less with temperature than the viscosity, the dampened turbulent mixing significantly reduces the Nusselt number, whereas the skin friction coefficient only marginally differs from the constant fluid property case. The attenuation of the radial velocity fluctuation consistently reduces the production terms in the budgets of the turbulent momentum and heat fluxes, while the production of the enthalpy fluctuations is only shifted away from the wall without significant change in peak level. The also attenuated redistribution in the turbulent axial stress budget reduces the pressure-strain based steering of turbulence towards isotropy. Facing a consequently more anisotropic turbulent motion poses a further difficulty to standard turbulence modelling mostly developed for isotropic turbulence.

NUMERICAL SIMULATIONS OF THE INFLUENCE OF VARIOUS PARAMETERS ON HEAT TRANSFER AND FLOW SEPARATION IN SUPERSONIC COOLED NOZZLES

In rocket engine nozzle design, flow separation is essential and, given the high temperatures and pressures in the thrust chamber, regenerative cooling is critical for maintaining the nozzle wall's integrity. This passage provides a summary of an in-depth numerical analysis of boundary layer separation and heat transfer within a 30°-15° cooled nozzle. The performance of the SST-V turbulence model under these conditions is assessed numerically. A variety of factors are investigated, including wall temperature, turbulent Prandtl number, and constant specific heat ratios (spanning 1.31 to 1.4 for constant fluid properties of N2O, CH4, Cl2, and air). Furthermore, variable specific heat ratios (from 1.39 to 1.66 for variable fluid properties of air, CH4, O2, and Helium) are examined, along with other parameters that affect the location of separated flow and the local wall heat transfer.

Similarity solutions of a Blasius flow with variable fluid properties and viscous dissipation

AbstractAn analytical model of the Blasius flow is studied including temperature-dependent fluid properties and viscous dissipation. The friction coefficient and Nusselt number at the wall are calculated from the resulting dimensionless velocity and temperature fields. The variable properties model is compared to a constant properties model to verify if and under which conditions this simplification is valid. Air, water and oil are analyzed as fluids over a representative operating regime, respectively. For air, the variable properties do not influence the friction coefficient and the Nusselt number. For water, the influence of the variable properties is present for both parameters but limited since no large temperature difference can occur in water without a phase change. New correlations for the friction coefficient and Nusselt number were derived for water and oil over a large range of operating conditions. Viscous dissipation does not significantly affect these parameters for air and water because of their relatively low Prandtl numbers. The high Prandtl number of oil in combination with a viscosity that is strongly decreasing with increasing temperature, leads to a more complex behavior. The friction coefficient as well as the Nusselt number are strongly dependent on the fluid properties. Dissipation effects cannot be neglected above an Eckert number of around 0.01. The superposition principle to evaluate wall heat flux in experiments is based on the assumption of constant fluid properties. It can be used without restrictions for air but should be thoroughly checked for all other fluids, especially liquids, using the presented methodology.

Entropy generation studies of turbulent fluid flow through novel hybrid corrugated channels with variable thermophysical properties

The investigation of the effects associated with the temperature-dependent property (viscosity, density and thermal conductivity) variations on fluid flow, entropy generation, and heat transfer in the various hybrid corrugated channels is performed numerically. Water enters the flow domain with a constant inlet temperature of 300[Formula: see text]K and constant inlet velocity corresponding to the different Re values. An in-depth numerical investigation is performed for the two cases that have the least entropy generation among all the cases and these cases are inward arc-outward triangular and inward trapezoidal-outward triangular corrugated channels. The use of corrugated channels with variable properties substantially affects the Nu. The effect of temperature-dependent property variation corresponding to the Re on frictional and heat transfer entropy generation is also presented in this work. The rise in the Re and consideration of variable fluid properties resulted in a decrement in the total entropy generation. Under the considered conditions, the frictional entropy generation contribution in the total entropy generation is very small as compared to the heat transfer entropy generation with constant and variable fluid properties. Furthermore, the consideration of temperature-dependent property variation results in a lower augmentation entropy generation number as compared to the constant property cases at higher Re.

A novel transfer matrix-based method for steady-state modeling and analysis of thermal systems

Performance analysis and optimization of thermal systems are unprecedentedly crucial in pursuing higher energy efficiency. However, the precise modeling and high-efficiency calculation of modern, complex thermal systems are still challenging. Here we present a transfer matrix-based system modeling method to tackle these challenges. The transfer matrix of heat exchangers is defined to describe the temperature mapping relation between inlet and outlet nodes. Heat-work conversion devices are described by the working fluid temperature variation. The system modeling follows a three-step procedure: (1) building system transfer matrix by aggregating component models; (2) separate given and unknown node temperatures by removing redundant rows and columns in the system transfer matrix; (3) rearrange the reduced system transfer matrix to calculate internal and outlet node temperatures. The constructed system model does not introduce unnecessary simplifications and describes the system’s nonlinearity accurately. The proposed modeling method is first presented and validated on a parallel-series and a multi-loop heat exchanger network. Numerical results with both constant and varying fluid properties confirm the method’s validity. Case studies on three thermodynamic systems further validate the method’s capability and efficiency. The proposed method is finally compared with conventional modeling methods and heat current method to highlight its features and advantages.

Fundamentals-Based Alternative Addresses Issue With Three-Phase Permeability Model

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 205883, “Issue With Stone II Three-Phase Permeability Model and a Novel Robust Fundamentals-Based Alternative to It,” by Subodh Gupta, SPE, Heretech Energy. The paper has not been peer reviewed. _ The objective of this paper is to present a fundamentals-based, three-phase flow model consistent with observation that avoids the pitfalls of conventional models. Though the use of the Stone II model is very popular for three-phase flow across the industry, one issue in the context of gravity drainage is how it appears counterintuitively to limit the flow of oil when water is present near its irreducible saturation. The novelty of the work presented in the complete paper is in the development of a model based on fundamentals of flow in fine channels that better explains observed results in the context of flow in porous media. Problem Definition Residual oil saturation (So) from retrieved cores from oil-drained chambers of steam-assisted gravity drainage (SAGD) reservoirs invariably shows values as low as 1 or 2%, whereas reservoir simulations using Stone II-based relative permeabilities (an industrywide favorite) predict significantly higher numbers (14–18%). In previous work, the author and others, in an attempt to remedy the situation, extended the oil-phase relative permeability in the presence of the water phase (krow) and oil-phase relative permeability in the presence of the gas phase (krog) curves all the way to water and gas saturation values less than unity; however, they discovered that, in the presence of water saturation (Sw) near the irreducible water saturation (Swi), the use of the Stone II formula for oil relative permeability still resulted in high residual So. Correct estimation of residual oil-phase saturation is even more important for solvent/steam mixed thermal recovery processes such as solvent-aided processes, where a small amount of solvent is added with steam in SAGD, and significantly more important for solvent-dominated processes, where a small amount of steam or heat is added with a large amount of solvent. A large amount of residual oleic-phase saturation and associated pessimistic solvent-recovery prediction will lead to erroneous economic assessment of these processes. The discrepancy in residual So, as the author and coauthors discovered in previous work, stems from a peculiarity of the Stone II formulation given by Equation 1 of the complete paper. To model this 1D problem numerically, a program developed by the author for his PhD thesis for modeling of moving front reservoir processes with dynamic gridding was modified and run with constant fluid properties for hexane and water at constant pressure and temperature. It also incorporated the three-phase relative permeabilities given by Equation 1 and Table 1 of the complete paper. The results are shown in Fig. 1.

Influence of Variable Viscosity on Entropy Generation Analysis Due to Graphene Oxide Nanofluid Flow

Conventional investigations on fluid flows are undertaken with an assumption of constant fluid properties. But in reality, the properties such as viscosity and thermal conductivity vary with temperature. In such cases, considering these variabilities aids in modelling the flows with accuracy. Particularly, studying the flow of graphene based nanofluids with variable properties makes the best of both the advantageous thermophysical properties of graphene nanoparticles in heat transfer and the variable fluid properties in accuartely modelling the flow. In this article, the flow of graphene oxide nanofluid along a linearly stretching cylinder under no-slip and convective boundary conditions is investigated, by taking the base fluid viscosity to be a temperature dependant function. Buongiorno model is adapted to develop the flow of graphene nanofluids including the influence of variable heat source, cross-diffusion effects and the effects of nanoparticle characteristics such as thermophoresis and Brownian motion. The modelled equations are transformed and are numerically solved using linearization method. The impacts of embedded parameters including the Dufour and Soret numbers on temperature, concentration and velocity profiles of the chosen nanofluid and their consequent impacts on the predominant cause for the generated entropy are studied. The obtained results are depicted and interpreted in detail. From the tabulated values of skin friction and the values of Sherwood and Nusselt numbers, it is inferred that the conductive heat and mass transfer can be enhanced by variable viscosity parameter and skin friction can be reduced by Soret number. Furthermore, entropy generation is analysed and Bejan number is calculated to be lesser than 0.5, thus demonstrating the dominance of irreversibilty to fluid friction and mass transfer.

DESIGN OF HELICAL TYPE STEAM GENERATOR FOR EXPERIMENTAL POWER REACTOR

Reaktor Daya Eksperimental (RDE) is a high-temperature gas-cooled reactor (HTGR) for electricity generation, heat generation, and hydrogen production by Batan. Empirical and numerical calculations are needed to strengthen the existing design. The numerical method by computational fluid dynamic (CFD) analyzes temperature distribution and pressure drop along the pipe. The Batan RDE steam generator design has a seven-layer helical pipe model, while this research uses a one-layer helix pipe. In empirical calculations, the heat transfer region has three sections; single-phase liquid, two-phase, and single-phase vapor heat transfer. In numerical calculations, apply the assumption of constant heat flux and constant working fluid properties. The results of empiric calculations data showed that the helical pipe height was 3.98 m, shorter than the Batan design, which is 4.97 m. This considerable difference due to empirical calculations did not cover the safety factor. The results of numerical calculations show that in the single-phase, empiric calculation data were acceptable since the different values of numerical calculations for empiric calculations data were below 10%. Meanwhile, the case of the two-phase numerical calculations is not satisfactory and needs further research to obtain optimal results.

Steady‐State Effective Normal Stress in Subduction Zones Based on Hydraulic Models and Implications for Shallow Slow Earthquakes

AbstractThe spatial distribution of effective normal stress, , is essential for understanding the fault motion. Although Rice (1992, https://doi.org/10.1016/s0074-6142(08)62835-1) proposed a steady‐state solution for a vertical strike‐slip fault zone with constant fluid properties, models that are based on the concept by Rice (1992, https://doi.org/10.1016/s0074-6142(08)62835-1) and are applicable for other tectonic settings have not yet been developed. Such a model is particularly important in subduction zones because the relationship between low and slow earthquakes is often discussed. To quantitatively examine the causes of a local decrease in on a shallow region of the subduction zone, we performed model calculations that incorporated mechanisms characteristic to subduction zones. Our basic model, which considers the effect of smectite dehydration and the mechanical effect of subduction, yields results that are consistent with those reported by Rice (1992, https://doi.org/10.1016/s0074-6142(08)62835-1): the gradient of remarkably decreases with the increase in depth, whereas the realistic fluid properties rule out nearly constant at depth. We obtained a monotonic increase in with the increase in depth for the physically sound solutions and failed to generate a local decrease in . The presence of a splay fault and fluid leakage though it cannot decrease locally. We found that a local decrease in permeability decreased locally around an impermeable zone and, thus, possibly led to the occurrence of shallow slow earthquakes. The water release caused by the dehydration reaction may not be the dominant factor, although smectite dehydration releases silica and promotes its precipitation.

Numerical investigation of heat transfer and fluid flow characteristics of ternary nanofluids through convergent and divergent channels.

The characteristics of nanomaterials have garnered significant attention in recent research on natural and forced convection. This study focuses on the forced convection characteristics of ternary nanofluids within convergent and divergent channels. The ternary nanofluid comprises titanium oxide (TiO2), zinc oxide (ZnO), and silver suspended in water, which serves as the base fluid. Using COMSOL Multiphysics 6.0, a reliable software for finite element analysis, numerical simulations were conducted for steady and incompressible two-dimensional flow. Reynolds numbers varying from 100 to 800 were employed to investigate forced convection. Additionally, we explored aspect ratios (channel height divided by the height of the convergent or divergent section) of -0.4, -0.2, 0, 0.2, and 0.4. Our findings revealed that only at aspect ratio a = 0.4 did the average outlet temperature increase as the Reynolds number rose, while other aspect ratios exhibited decreasing average temperatures with declining Reynolds numbers. Moreover, as the Reynolds number increased from 100 to 800 and the total volume fraction of the ternary nanofluids ranged from 0.003 to 0.15, there was a significant 100% enhancement in the average Nusselt number. For clarity, this article briefly presents essential information, such as the study's numerical nature, fluid properties (constant-property fluid), and the methodology (COMSOL Multiphysics 6.0, finite element analysis). Key conclusions are highlighted to enable readers to grasp the main outcomes at a glance. These details are also adequately covered in the manuscript to facilitate a comprehensive understanding of the research. The utilization of this emerging phenomenon holds immense potential in various applications, ranging from the development of highly efficient heat exchangers to the optimization of thermal energy systems. This phenomenon can be harnessed in scenarios in which effective cost management in thermal production is a critical consideration.

Three-dimensional wake transition for CO2 flow at supercritical pressure over single heated cylinder

The three-dimensional wake transition for supercritical CO2 (SCO2) with Reynolds number (Re) ranging from 100 to 300 is systematically investigated by large eddy simulation. Numerical results of the constant-property fluid are validated with the classical conclusions. The secondary instabilities, i.e., mode A (spanwise scale of ∼4.5 times cylinder diameter) and mode B (approximately equal to cylinder diameter), are well captured in the wake. The results at Re = 120 show that the evolution of vortex dislocations is mainly manifested in the alternating occurrence of three stages, i.e., the two-dimensional vortex shedding stage, pure mode A stage, and dislocation stage. The stable state of pure mode A is found at Re = 140. As Re continues to increase, the wake shows a gradual transition from mode A to mode B, rather than the transition from mode A* (mode A + dislocation) to mode B. The frequency spectrum in this process is the gradual shift of a single peak from the low frequency to the high frequency. The wake cycle sequence changes from the alternation of four structures at Re = 155 to the alternation of pure and “contaminated” mode B structures at Re = 170. The critical condition of wake “resonance” is determined at Re = 175, where the final state of the wake is relatively ordered mode B structure, representing the weakest three-dimensionality in the transition regime. After that, the three-dimensionality of the wake enhances with Re, and the probability of the occurrence of disordered structures increases accordingly. The vortex shedding frequency of the pure mode follows the order: 2D > B > A > A*. The width of the frequency spectrum is mainly related to whether the wake flow state is a continuous single mode or the alternation of multiple modes. Based on the Strouhal–Reynolds number relationship, flow pattern in the wake transition process is finally discussed.

Mechanistic model of combined pressure drop and heat transfer for the entire growth stage of an elongated bubble in a rectangular microchannel

A one-dimensional flow-boiling model for the slug-flow regime is formulated to describe the pressure drop and heat transfer mechanism in a microchannel of rectangular cross-section. The pressure drop model considers three stages of bubble growth namely: (i) partial confinement, (ii) full confinement and (iii) vapour venting. The heat transfer coefficient at any particular location is obtained by assuming the periodic passage of four zones: (i) liquid slug zone, (ii) elongated bubble zone, (iii) partially dryout zone, and (iv) fully dryout zone. The model is evaluated using constant fluid properties, to study the parametric variation of channel pressure drop and heat transfer coefficient. The effects of variation in channel dimension, flow velocity, heat flux and properties of working fluid on pressure drop and heat transfer coefficient have been studied using the model. The model is capable of simulating all the transport processes for a single bubble from its inception till it leaves the microchannel and thereby it can estimate the pressure drop in the channel along with the heat transfer coefficient i.e. spatially averaged over the channel length and at any location from channel upstream to the downstream end.

Unsteady forced convection flow and heat transfer past a blunt headed semicircular cylinder at low Reynolds numbers

A numerical analysis is performed to study the forced convective fluid flow and heat transfer past an unconfined semicircular cylinder. The two-dimensional simulations are carried out for Reynolds number ranging 10 ≤ Re ≤ 200 and operating fluid is air (Pr = 0.71) for Newtonian constant property fluid. Continuity, Navier-Stokes, and energy equations with appropriate boundary conditions are solved using computational fluid dynamics solver Ansys Fluent. Various parameters flow such as lift, drag, skin friction coefficient, pressure coefficient, Nusselt (Nu) number, Strouhal (St) number, and vortex strength are calculated. The transition from steady to time periodic flow occurs between Re = 60 and 80. The effect of Reynolds number on heat transfer is discussed. Finally, a developed correlation of Nu and St numbers are presented.

Reference temperature correction and dimensionless number analysis for heat transfer of supercritical CO2 in horizontal tubes

Researchers have extensively studied convective heat transfer of variable property fluids in tubes because of their different heat transfer characteristics to constant property fluids. However, the heat transfer correlations are often limited to small or large tubes or other limited conditions when the properties of fluids change dramatically, which may be due to inaccuracy definition of the reference temperature in average heat transfer coefficient (HTC) and incorrect understanding of dimensionless parameters in Nusselt correlation.As a typical case, this study numerically investigates the cooling heat transfer of sCO2 in horizontal tubes near the pseudo-critical point. Eight numerical models are compared with experimental results in the literature, and the Realizable k–ε model with enhanced wall treatment is best for predicting cooling HTC. A new definition of reference temperature for average HTC is proposed, which is more accurate than the traditional arithmetical average of inlet and outlet bulk temperature. Sensitivity analysis of HTC is carried out for heat transfer mechanisms. In addition, the definitions of dimensionless numbers in Nusselt correlation are analyzed, and more accurate definitions are proposed. Based on the conclusions, a newly developed Nusselt correlation with concise form shows excellent results with a Root Mean Square (RMS) error of 2.9% for 6.22 and 9.40 mm tubes. It can still maintain high accuracy when it is extrapolated to 4.15 and 14 mm tubes. The numerically derived correlation agrees well with the experimental results for 2–6 mm tubes in literature and can also be extrapolated to constant property cases.

Application of Superposition Principle for Solving a Nonlinear Energy Equation

Abstract A new procedure to solve a nonlinear energy equation using the superposition principle is proposed. As an example of the utilization of this procedure, forced convection in a tube with temperature-dependent fluid properties was considered. The tube wall was maintained at uniform wall heat flux axially that varies with time, and the average fluid temperature at the outlet was calculated. This problem simulates convection heat transfer inside a solar collector tube. In the proposed procedure, the average fluid temperature at the outlet for a single heat pulse was determined for fluid properties evaluated at 15 different temperatures by solving the energy equation numerically assuming constant fluid properties and subsequently applying the superposition principle. The choice of the temperature at which fluid properties were evaluated as an important parameter in the simulation. This temperature was determined by using the inlet and outlet average fluid temperatures at the previous time-step multiplied by a weighting function. The average fluid temperature at the outlet obtained by this procedure was compared with the temperature obtained by solving the nonlinear energy equation using variable properties to determine the predictive accuracy of this procedure. The results for one-day operation of a sunny day with fluid velocity of 0.6 m/s, showed the highest root-mean-square (RMS) error of 0.25 K, and the highest mean absolute deviation (MAD) error of 0.16 K which agreed well with the result obtained by the numerical simulation of the nonlinear problem using variable properties.

Heat transfer past rotationally oscillating circular cylinder heated with time‐periodic pulsating temperature in a uniform flow

AbstractThe transient forced convection heat transfer from an impulsively started rotationally oscillating circular cylinder, heated with time‐periodic pulsating temperature in a two‐dimensional uniform, laminar and viscous flow of Newtonian, incompressible, constant property fluid is investigated in this paper. The two‐dimensional Navier‐Stokes and energy equations are solved using a higher‐order compact (HOC) finite difference scheme on non‐uniform polar grids. Computational code for solving the problem is written in C programming language and is validated against existing research works. The flow and heat transfer characteristics are mainly influenced by the amplitude of time‐periodic pulsating temperature (), period of time‐periodic pulsating temperature (), Prandtl number (), Reynolds number (), and cylinder oscillation parameters i.e. maximum rotational rate (), frequency ratio (). The numerical computations are done for the range of parameter values , , , , and . The backward heat transfer is observed for certain values of the amplitude of time‐periodic pulsating temperature and the amount of backward heat transfer enhances with increasing amplitude of temperature. High period value () of pulsating temperature is found to reduce the amount of heat convection downstream. The influence of pulsating temperature is discussed for an increase or decrease in heat transfer rate relative to the constant cylinder‐temperature case.

Numerical Simulation of Laminar Boundary Layer Flow Over a Horizontal Flat Plate in External Incompressible Viscous Fluid

In this paper, steady laminar boundary layer flow of a Newtonian fluid over a flat plate in a uniform free stream was investigated numerically when the surface plate is heated by forced convection from the hot fluid. This flow is a good model of many situations involving flow over fins that are relatively widely spaced. All the solutions given here were with constant fluid properties and negligible viscous dissipation for two-dimensional, steady, incompressible laminar flow with zero pressure gradient. The similarity solution has shown its efficiency here to transform the governing equations of the thermal boundary layer into a nonlinear, third-order ordinary differential equation and solved numerically by using 4th-order Runge-Kutta method which in turn was programmed in FORTRAN language. The dimensionless temperature, velocity, and all boundary layer functions profiles were obtained and plotted in figures for different parameters entering into the problem. Several results of best approximations and expressions of important correlations relating to heat transfer rates were drawn in this study of which Prandtl’s number to the plate for physical interest was also discussed across the tables. The same case of solution procedure was made for a plane plate subjected to other thermal boundary conditions in a laminar flow. Finally, for the validation of the treated numerical model, the results obtained are in good agreement with those of the specialized literature, and comparison with available results in certain cases is excellent.