Fluid Flow Analysis Research Articles

Lie group analysis of upper convected Maxwell fluid flow along stretching surface

In this article, significance of inclined magnetohydrodynamic flow of an upper-convected Maxwell (UCM) liquid along a penetrable stretched plate is explored. Heat transfer phenomenon is studied with heat generation and absorption effect. We utilize Lie group methodology for adaptation of non-linear differential equations and calculate its absolute invariants explicitly. A numerical method, namely the fourth-order Runge Kutta algorithm with shooting technique is used to solve non-linear ordinary differential equations along with boundary conditions. Velocity profiles for flow of Newtonian and UCM liquid are compared. Plots reflecting effect of inclined and non-inclined MHD for the variations of various parameters are explored and examined. It is observed that oposite behaviour occurs corresponding to heat absorption and generation parameter for both cases of inclination and non-inclination MHD.

Investigation of micropolar hybrid ferrofluid flow over a vertical plate by considering various base fluid and nanoparticle shape factor

PurposeThe purpose of this paper is to investigate micropolar magnetohydrodynamics (MHD) fluid flow passing over a vertical plate. Three different base fluids have been used that include water, ethylene glycol and ethylene glycol/water (50%–50%). Also, a nanoparticle was used in all of the base fluids. The effects of natural convection heat transfer and magnetic field have been taken into account.Design/methodology/approachThe main purpose of solving the governing equations is to scrutinize the effects of the magnetic parameter, the nanoparticle volume fraction, micropolar parameter and nanoparticles shape factor on velocity, temperature and microrotation profiles, the skin friction coefficient and the Nusselt number. These surveys have been considered for three base fluids simultaneously.FindingsThe results indicate that for water-based fluids, the temperature profile of lamina-shaped nanoparticles is 38.09% higher than brick-shaped nanoparticles.Originality/valueThis paper provides micropolar MHD fluid flow analysis considering natural convection heat transfer and magnetic field in three different base fluids. The aim of assessments is the diagnosis of some parameter effects, such as magnetic parameter and nanoparticle volume fraction, on velocity, temperature and microrotation profiles and components. Also, the use of mixed base fluids presented as a novelty in this paper.

Coupling Microfluidics Data with Core Flooding Experiments to Understand Sulfonated/Polymer Water Injection.

The injection of sulfonated-modified water could be an attractive application as it results in the formation of a mechanically rigid oil-water interface, and hence, possible higher oil recovery in combination with polymer. Therefore, detailed experimental investigation and fluid-flow analysis into porous media are required to understand the possible recovery mechanisms taking place. This paper evaluates the potential influence of low-salt/sulfate-modified water injection in oil recovery using a cross-analyzed approach of coupled microfluidics data and core flooding experiments. Fluid characterization was achieved by detailed rheological characterization focusing on steady shear and in-situ viscosity. Moreover, single and two-phase micromodels and core floods experiments helped to define the behavior of different fluids. Overall, coupling microfluidics, with core flooding experiments, confirmed that fluid-fluid interfacial interaction and wettability alteration are both the key recovery mechanisms for modified-water/low-salt. Finally, a combination of sulfate-modified/low-salinity water, with polymer flood can lead to ~6% extra oil, compared to the combination of polymer flood with synthetic seawater (SSW). The results present an excellent way to make use of micromodels and core experiments as a supporting tool for EOR processes evaluations, assessing fluid-fluid and rock-fluid interactions.

Parallelization of Numerical Conjugate Heat Transfer Analysis in Parallel Plate Channel Using OpenMP

Conjugate heat transfer and fluid flow is a common phenomenon occurring in parallel plate channels. Finite volume method (FVM) formulation-based semi-implicit pressure linked equations algorithm is a common technique to solve the Navier–Stokes equation for fluid flow simulation in such phenomena, which is computationally expensive. In this article, an indigenous FVM code is developed for numerical analysis of conjugate heat transfer and fluid flow, considering different problems. The computational time spent by the code is found to be around 90% of total execution time in solving the pressure (P) correction equation. The remaining time is spent on U, V velocity, and temperature (T) functions, which use tri-diagonal matrix algorithm. To carry out the numerical analysis faster, the developed FVM code is parallelized using OpenMP paradigm. All the functions of the code (U, V, T, and P) are parallelized using OpenMP, and the parallel performance is analyzed for different fluid flow, grid size, and boundary conditions. Using nested and without nested OpenMP parallelization, analysis is done on different computing machines having different configurations. From the complete analysis, it is observed that flow Reynolds number (Re) has a significant impact on the sequential execution time of the FVM code but has a negligible role in effecting speedup and parallel efficiency. OpenMP parallelization of the FVM code provides a maximum speedup of up to 1.5 for considered conditions.

A New Vacuum System for Steam Plant Condenser

Abstract In the current work, a simple and low energy consuming system is proposed for holding on the vacuum in the steam power plant system. The vacuum is created at the tip of an inverted U-pipe through which water flows by siphon effect due to the height difference in water surfaces of two tanks. This height difference and the elevation of the inverted U-pipe tip define the value of the vacuum to be grown. The U-pipe tip is connected to the discharge pipe of a compressor which draws a mixture of air, and water vapor from the steam condenser and raises their pressure a little higher than that of the inverted U-pipe tip. The mixture flows with the water down the inverted U-pipe till they depart the U-tube. A thermodynamic and fluid flow analysis is developed for predicting the performance of the proposed system. The results of this analysis show that the right selection of the mass flowrate ratio of water flowing in the inverted U-pipe to air and water vapor mixture sucked by the compressor from the steam plant condenser, in the range of 25,000, the height of the inverted U-pipe summit from the water level of the higher water tank greater than 9.2 m and the height difference of the water levels in the two water tanks small enough, in the range of 0.1 m saves the power of vacuum system by 80% less than that consumed when using compressor alone for venting the steam plant condenser.

Numerical manifold method modeling of coupled processes in fractured geological media at multiple scales

The greatest challenges of rigorously modeling coupled hydro-mechanical (HM) processes in fractured geological media at different scales are associated with computational geometry. These challenges include dynamic shearing and opening of intersecting fractures at discrete fracture scales as a result of coupled processes, and contact alteration along rough fracture surfaces that triggers structural and physical changes of fractures at micro-asperity scale. In this paper, these challenges are tackled by developing a comprehensive modeling approach for coupled processes in fractured geological media based on numerical manifold method (NMM) at multiple scales. Based on their distinct geometric features, fractures are categorized into three different scales: dominant fracture, discrete fracture, and discontinuum asperity scales. Here the scale is relative, that of the fracture relative to that of the research interest or domain. Different geometric representations of fractures at different scales are used, and different governing equations and constitutive relationships are applied. For dominant fractures, a finite thickness zone model is developed to treat a fracture as a porous nonlinear domain. Nonlinear fracture mechanical behavior is accurately modeled with an implicit approach based on strain energy. For discrete fractures, a zero-dimensional model was developed for analyzing fluid flow and mechanics in fractures that are geometrically treated as boundaries of the rock matrix. With the zero-dimensional model, these fractures can be modeled with arbitrary orientations and intersections. They can be fluid conduits or seals, and can be open, bonded or sliding. For the discontinuum asperity scale, the geometry of rough fracture surfaces is explicitly represented and contacts involving dynamic alteration of contacts among asperities are rigorously calculated. Using this approach, fracture alteration caused by deformation, re-arrangement and sliding of rough surfaces can be captured. Our comprehensive model is able to handle the computational challenges with accurate representation of intersections and shearing of fractures at the discrete fracture scale and rigorously treats contacts along rough fracture surfaces at the discontinuum asperity scale. With future development of three-dimensional (3D) geometric representation of discrete fracture networks in porous rock and contacts among multi-body systems, this model is promising as a basis of 3D fully coupled analysis of fractures at multiple scales, for advancing understanding and optimizing energy recovery and storage in fractured geological media.

Scaling group analysis of bioconvective micropolar fluid flow and heat transfer in a porous medium

The current and potential applications of bioconvection renewed drive for theoretical research on synthesis and process control in biofuel cells and bioreactors. Thus, this work devoted to solving the problem of free convection in micropolar boundary layer fluid flow and heat transfer past a vertical flat stretching plate within a porous medium. Scaling group of transformation was performed to achieve the appropriate similarity solutions, which was later applied to modify the governing boundary layer system to a nonlinear ordinary differential equations system. The Runge–Kutta method in association with the shooting technique in the Maple software exercised to attain the numerical solutions. There is a strong dependence of momentum transportation on the increment of the Darcy number, the suction/injection parameter and the Grashof number, respectively. The temperature distribution within the thermal boundary layer aided by augmenting the magnitude of the microrotation density.

Analysis of MHD Fluids around a Linearly Stretching Sheet in Porous Media with Thermophoresis, Radiation, and Chemical Reaction

This paper presents the comparative analysis of MHD boundary layer fluid flow around a linearly stretching surface in the presence of radiative heat flux, heat generation/absorption, thermophoresis velocity, and chemical reaction effects in a permeable surface. The governing equations are highly nonlinear PDEs which are converted into coupled ODEs with the help of dimensionless variables and solved by using semianalytical techniques. The numerical and graphical outcomes are observed and presented via tables and graphs. Also, the Nusselt and Sherwood numbers and skin friction coefficient are illustrated by tables. On observation of heat and mass transfer, it was noticed that Maxwell fluid dominates the other fluids such as Newtonian, Williamson, and Casson fluid due to high rate of thermal conductivity, and hence, Maxwell fluid has better tendency for heat and mass transfer than other Newtonian and non-Newtonian fluids.

Optimization of Hole Diameter on Fins of Si Engine through Numeraical Analysis

Fuel and material cost is increasing day by day in all the industries. In IC engine, engine fails mainly due insufficient of heat transfer from the cylinder wall to the atmospheric air. In SI engine, heat is extracted from the cylinder wall by convection heat transfer through the fins. In this paper optimal hole size on the fins is obtained in order to extract the heat from the engine by numerical method. ANSYS is used to find the temperature distribution on the fins , when there no holes, when there is hole diameter as 2mm, 2.5mm,3 mm, 3.5mm,3.8mm, 4mm and two row holes of 3.5 mm diameter. For this analysis fluid flow (fluent) is chosen, air is circulated on engine with 16.666 m/s velocity and with atmospheric pressure. Temperature value of 800K is applied to the cylinder wall. Temperature is compared with the all hole diameter cases, and it is found that the 3.5 mm diameter hole gives the best results compare to all other hole diameter. The temperature difference 0.04K is obtained between without holes and with 3.5 mm diameter. The 3.5 mm diameter hole fins are used where material cost goes at high rate.

Heat and mass transfer analysis of casson fluid flow on a permeable riga-plate

Numerical analysis has been carried out for a casson fluid flow on a riga-plate with temperature dependent thermal conductivity. The physical model which governs the transport properties is solved numerically. This investigation emphasizes the consequence of variable thermal conductivity and electrically conducting magnetic field on the fluid flow. Rate of heat transfer is elevated, while the flow exposed to constructive case of variable thermal conductivity. The flow speed is enhanced for the improved values of modified Hartmann number. Correlation of the results with the similarity solutions declares the accuracy.

Heat and mass transfer and thermodynamic analysis of power-law fluid flow in a porous microchannel

Transfer of heat and mass and thermodynamic irreversibilities are investigated in a porous, parallel-plate microreactor in which the working fluid is non-Newtonian. The investigated microreactor features thick flat walls with uneven thicknesses, which can be subject to different thermal loads. The dimensionless governing equations of the resultant asymmetric problem are first derived theoretically and then solved numerically by using a finite volume technique. This results in two-dimensional solutions for the velocity, temperature and concentration fields as well as the distributions of Nusselt number and local and total entropy generations. The results clearly demonstrate the significance of the numerical value of the power-law index and departure from Newtonian behavior of the fluid. In particular, it is shown that by increasing the value of power-law index the Nusselt number on the wall decreases. This leads to the intensification of the temperature gradients in the system and therefore magnifies the local and total entropy generations. Also, it is shown that the wall thickness and thermal asymmetry can majorly affect the heat transfer process and thermodynamic irreversibility of the microreactor. It is noted that the current work is the first comprehensive study of heat transfer and entropy generation in porous micro-chemical reactor with non-Newtonian, power-law fluid.

Numerical approach of variable thermophysical features of dissipated viscous nanofluid comprising gyrotactic micro-organisms

This article addresses the heat and mass transport phenomena by performing a theoretical analysis of three-dimensional viscous fluid flow containing gyrotactic micro-organisms over a nonlinear stretched surface. Variable magnetic field is considered normal to the stretched surface to control the fluid flow. Thermal transportation is discussed in view of variable thermal conductivity. Variable characteristics of mass diffusion along with chemical reaction are incorporated in mass transportation. Darcy–Forchheimer expression is used to characterise the porous medium. Also, Brownian motion and thermophoresis are incorporated to enhance the diffusion. The governing partial differential equations (PDEs) are derived using boundary layer analysis by assuming small magnetic Reynolds number. Appropriate transformation is used to convert complex system of coupled PDEs into nonlinear ordinary differential equations (ODEs). Transformed problem is then tackled analytically using optimal homotopic procedure. Reliability of the suggested scheme is presented through error reduction table and also by comparing the obtained solution with the published ones. Graphs and tables are prepared to observe the impact of parameters on physical variables. Dimensionless stresses and rate of heat transfer are computed numerically. It has been observed that larger values of Brownian diffusion and thermophoresis increase the fluid temperature. Moreover, dimensionless stresses and rate of heat transfer are computed to check the reliability of the proposed procedure. These values are clearly in an excellent agreement with the previous findings reported in literature.

Computational analysis of time-dependent viscous fluid flow and heat transfer

The flow of viscous fluid between two parallel plates is investigated. The applications of the magnetic field effect have been considered in the vertical direction to the plates. Velocity has been presented in the presence of suction and injection. The temperature equation is assisted with the Joule heating effect. One of the numerical techniques, that is, finite difference approach has been used to tackle the given partial differential system. This method results in a system of simple algebraic equations. The unknown function is analyzed inside the domain. In this technique of solution, a system is subdivided into many smaller parts called finite elements. The obtained simpler algebraic equations are then assembled to form a system of equation which governs the original problem. The variational method is used to get an approximate solution by reducing the error function. The effects of pertinent variables on temperature and velocity are shown graphically in the discussion section. The obtained results show that the velocity decreases with magnetic and porosity parameters. Temperature increases for larger values of Hartmann and Eckert numbers.

Innovative Design and Implementation of Jet Cooling of Large UPS Powered Systems in Nuclear Power Plant

In this article, it is imperative that an efficient and reliable cooling system is used for the large Uninterrupted Power Supply (UPS) panel in Nuclear Power Plant. While the UPS system can tolerate relatively high temperatures, it is advisable to keep the temperature at 25 °C or below in the room where the UPS is housed. A rule of thumb is that for every 10 °C increase in operating temperature, the expected life of the UPS components would be reduced in half. So it is absolutely necessary to maintain the temperature within the limits prescribed by the designer. The aim of this article is to devise a vastly improved cooling system by streamlining the cool air flow and targeting the hotspots of the UPS components which are particularly vulnerable to damage from high temperature. First, a computational model of the whole setup was made and then, computational fluid dynamics (fluent) technique was used to perform fluid flow and heat transfer analysis of this setup, which showed a dramatic performance increase in the heat exchange process and reduced the effective size of the UPS cabin and cost.

Triple Solutions and Stability Analysis of Micropolar Fluid Flow on an Exponentially Shrinking Surface

In this article, we reconsidered the problem of Aurangzaib et al., and reproduced the results for triple solutions. The system of governing equations has been transformed into the system of non-linear ordinary differential equations (ODEs) by using exponential similarity transformation. The system of ODEs is reduced to initial value problems (IVPs) by employing the shooting method before solving IVPs by the Runge Kutta method. The results reveal that there are ranges of multiple solutions, triple solutions, and a single solution. However, Aurangzaib et al., only found dual solutions. The effect of the micropolar parameter, suction parameter, and Prandtl number on velocity, angular velocity, and temperature profiles have been taken into account. Stability analysis of triple solutions is performed and found that a physically possible stable solution is the first one, while all leftover solutions are not stable and cannot be experimentally seen.

Nonlinear Finite Element Analysis-Based Flow Distribution and Heat Transfer Model

A new strategy for fast, approximate analyses of fluid flow and heat transfer is presented. It is based on Finite Element Analysis (FEA) and is intended for large yet structurally fairly simple heat transfer equipment commonly used in process and power industries (e.g., cross-flow tube bundle heat exchangers), which can be described using sets of interconnected 1-D meshes. The underlying steady-state model couples an FEA-based (linear) predictor step with a nonlinear corrector step, which results in the ability to handle both laminar and turbulent flows. There are no limitations in terms of the allowed temperature range other than those potentially stemming from the usage of fluid physical property computer libraries. Since the fluid flow submodel has already been discussed in the referenced conference paper, the present article focuses on the prediction of the tube side and the shell side temperature fields. A simple cross-flow tube bundle heat exchanger from the literature and a heat recovery hot water boiler in an existing combined heat and power plant, for which stream data are available from its operator, are evaluated to assess the performance of the model. To gain further insight, the results obtained using the model for the heat recovery hot water boiler are also compared to the values yielded by an industry-standard heat transfer equipment design software package. Although the presented strategy is still a “work in progress” and requires thorough validation, the results obtained thus far suggest it may be a promising research direction.

Effective stress jump across membranes

A macroscopic condition to simulate the interaction between an incompressible fluid flow and a permeable micro-structured rigid surface (i.e. a thin membrane) has been developed using multiscale homogenization and matching asymptotic expansions between the near membrane and the far region. The condition allows us to write the fluid velocity across the membrane, seen macroscopically as a smooth equivalent surface, as an effective jump between the stresses computed on the two faces of this surface. The coefficients appearing in the jump condition are the entries of tensors which solve Stokes problems within the pores, enforced by boundary conditions depending on the flow outside the membrane. These problems, found via homogenization, definitely characterize the microscopic geometrical properties of thin permeable micro-structured sheets. The new macroscopic model is validated by comparisons with direct numerical simulations of the fluid flow across membranes in different configurations, proving that the formalism adopted to write the jump conditions is valid. As a result, a rational tool able to join a microscopic and a macroscopic analysis of fluid flows across membranes is delivered, showing some potentialities to provide advancement in membrane design. It suggests that the concept of permeability has to be substituted by a more general tensor, called here the Navier tensor, which plays the role of permeability only in some particular situations.

Optimisation of Automobile Radiator by Linear and Helical Tubes

An automobile radiator is a component of an automotive cooling system which plays a major role in transferring the heat from the engine parts to the environment through its complex working system. Heat losses through the radiator and the tailpipe add up to 58 to 62 percent of the total losses. Insufficient heat dissipation can result in the overheating of the engine, which leads to the breakdown of the lubricating oil, corrosion and metal weakening of engine parts, and significant wear between engine parts. To minimize the stress on the engine as a result of heat generation, automotive radiators must be designed to be more effective while still maintaining high level of heat transfer within components. This leads to the increased demand of power packed radiators, which can dissipate maximum amount of heat for any given space. In this paper we have designed and analyzed the performance of radiators by comparing linear tube radiator and two helical tube radiators as coolant inside radiator follows triple pass flow pattern. The modeling is done using CATIA. The fluid flow analysis is done with ANSYS FLUENT.

Experimental and Numerical Analysis of Fluid Flow in Microfibers

The flow in small geometries is of interest in applications like bioanalysis systems, micro-valves and flow through porous media. The flow generally straight- forward to predict since the flow is stratified and so the geometries are clear-cut. However, once it involves flow through twin scale porous media, the flow gets harder to predict. The flow-through porous media are usually applied to areas like composites manufacturing, paper making and drying of ore pellets. The aim of this paper is to check flows in small geometries with numerical and experimental ways to realize an enlarged understanding of porous media flow. The optical technique best fitted to this sort of geometries is micro image velocimetry (μ-PIV) and numerical calculations are done with computational fluid dynamics (CFD). μ-PIV is employed to analyze the flow in channels with one fiber and with fiber arrays of various patterns and densities. The impact consistency has on flow fields in channels is investigated with CFD.

Entropy analysis of EMHD non-Newtonian fluid flow induced by Riga plate with slip and convective boundary phenomena

Our paper is consecrated to show the influence of variable fluid properties in EMHD non-Newtonian power-law fluid along a moving Riga plate. Slip velocity phenomenon is considered at the surface which is convectively heated. Entropy analysis is elaborated employing thermodynamic second relation. The governing nonlinear PDEs are altered into ODEs through adequate propinquity transformations which have been solved numerically via the shooting method with the fourth-order Runge–Kutta algorithm through Mathematica software (bvp4c). Characteristics of different basic parameters on velocity, temperature, entropy generation and Bejan number are highlighted through graphs. The outcomes exhibit that the minimum entropy rate in the flow system can be obtained either with rising viscosity parameter and slip parameter or declining dimensionless parameter and thermal conductivity parameter. The entropy rate is minimal for dilatant fluid when compared to pseudo plastic fluid with the most governing parameters. Contrast behavior on the thermal field is noticed for larger values of viscosity parameter and thermal conductivity parameter.