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The outputs of CVFEM modeling of MHD convection flow of hybrid nanomaterial has been reported in current article. To convert the problem more applicable, permeability and Lorentz terms have been involved in estimation of flow structure. To reduce the computational cost, one scalar has been eliminated with defining vorticity formula and radiation term was imposed in temperature distribution. Outcomes demonstrated that as Darcy augments, the interaction of nano powders to elliptic surface augments which means smoother detach of boundary layer. Therefore, permeability is an augmenting function of ψand Nu and in presence of Ha, this impact decreases. Nu tends to reduce if radiation term involved in energy equation and increasing Ha makes this reducing trend weaker. Although the Joule impact was neglect and magnetic has no term in energy equations, isotherms have been affected by Ha due to reduction of velocity of nanomaterial.

The paper presents a numerical study of the discharged heat water effect on the aquatic environment from the thermal power plant by using two water discharged pipes. It is solved by the Navier–Stokes and temperature transport equations for an incompressible fluid in a stratified medium. The aim of this study is to improve the existing water discharge system to reduce the heat load on the reservoir-cooler of the thermal power plants operation (Ekibastuz SDPP-1). In this study thermal pollution to the reservoir-cooler using only two water discharged pipes as so using the existing one and building only one additional in the eastern part of the reservoir-cooler is numerically simulated. The numerical method is based on the projection method which was approximated by the finite volume method. The numerical solution of the equation system is divided into four stages. The algorithm is parallelized on a high-performance computer. The obtained numerical results of three-dimensional stratified turbulent flow for two water discharged pipes of the thermal power plant were compared with experimental data and with numerical results for one water discharged pipe. General thermal load in the reservoir-cooler decreases comparing one water discharged pipe and revealed qualitatively and quantitatively approximately the basic laws of hydrothermal processes occurring in the reservoir-cooler can be seen that from numerical simulations where two water discharged pipes were used.

This paper presents the results of a numerical study of urban pollution climatologies using green barriers. Nowadays urban climatology is becoming a hot topic. Air quality has a significant impact on human health. For the numerical solution of this problem, the test problem was solved. To assess the applicability of the mathematical model, the numerical algorithm and the choice of the optimal turbulent model, experimental data and numerical calculations by other authors were used. The obtained numerical simulation results are in good agreement with the experimental results and the numerical results of other authors. And to obtain more accurate numerical results for the experimental data, there was a certain corresponding turbulent model. Further, for all numerical solutions, a certain optimal turbulent DES model was used. And also the influence of green continuous and discontinuous barriers on the concentration distribution was considered. To reveal the optimum barrier height, experimental data were used. As a result of the concentration spread between the continuous and the discontinuous barrier, there is a significant difference in the dependence on the height of the barrier and the concentration of pollutants at ground level decreases as compared to the green discontinuous barrier. The results can help city planners in green infrastructure and protect urban climatologies from pollution.

Neutron diffraction is one of the best methods for structural analysis of a complex, layered perovskite material with low symmetry by accurately detecting the oxygen positions through octahedral tilting. In this research, the crystal structure of NdSrMn2O5+δ was identified through X-ray diffraction (XRD) and neutron powder diffraction (NPD) at room temperature (RT), which indicated the formation of a layered structure in orthorhombic symmetry in the Pmmm (no. 47) space group. Rietveld refinement of the neutron diffraction data has confirmed the orthorhombic symmetry with unit cell parameters (a = 3.8367 (1) Å, b = 3.8643 (2) Å, and c = 7.7126 (1) Å), atomic positions, and oxygen occupancy. Thermogravimetric analysis revealed the total weight loss of about 0.10% for 20–950°C temperature, which occurred mainly to create oxygen vacancies at high temperatures. Rietveld analyses concurred with the XRD and neutron data allowing correlation of occupancy factors of the oxygen sites.

In this paper, was presented the numerical simulation of air pollution by particles with different sizes from the Ekibastuz State district power plant-1 (Ekibastuz SDPP-1), which is located on the northern side of Zhyngyldy Lakeshore, the Republic of Kazakhstan in real scales using the three-dimensional mathematical model. It was found that the deterioration of the environment is due to the release of a large amount of SOx, NOx and the volatile particles of Suspended Particulate Matter and Respirable Suspended Particles matter (SPM and RSPM), which cause human and animal diseases The experimental data were used to evaluate the applicability of the mathematical model and the numerical algorithm for the test problem. The obtained numerical simulation results are in good agreement with the numerical results of other authors and the experimental data. In addition, to select the optimal turbulent model, the obtained simulation results for different turbulent models were compared with experimental data.

In this attempt, melting of PCM due to hot air from ambient within sunny day has been scrutinized. To bring the opportunity for PCM to observe more heat from hot air flow, nanoparticles was dispersed in to RT28. To augment the effective surface the duct was fabricated with sinusoidal walls. Outputs demonstrate the liquid fraction and heat flux as well as temperature distribution. At t = 40 h and a = 5, Liquid fraction reaches to 0.9 and such values increase to 0.97 if a augments to 10 mm. When a = 10, liquid fraction at t = 40 h, 5.91 times greater than that of t = 5 h. Q profile for both cases reduced with augment of time but different behavior was reported for effect of amplitude. Greater values of a, provides higher Q when t 31 h. Heat flux augments about 2.9% with augment of amplitude of wavy wall.

Variations of needed time for full solidification with impose of fins and various sizes of nanoparticles is main goal of current article. Not only the needed time values but also, contours and solid front configurations were depicted in outputs which were obtained from (Finite element method) FEM modeling. Diameter of particles has various impact of thermal features and finding the best design needs considering various values of dp. Time increases about 16.09% with augment of dp from 30 to 50 nm. So, it is not recommended to rise dp upper than 40 nm. Selecting dp = 40 nm instead of 30 nm results in 16.91% augmentation in solidification rate. To reduce the time of discharging to 614.8 s, the case with greatest length and dp = 40 nm should be selected. There was about 5.86% reduction in discharging time with augment of L. The minimum temperature of storage unit was obtained for dp = 40 nm and same behavior is examined for values of energy.

Energy is a main factor for sustainable and economic development of many countries in the world. The objective of this paper is to investigate barriers facing solar energy development in Iran through a case study conducted on the Alborz Province. A questionnaire was designed and then submitted to the professionals in the field of solar energy. First, the identified barriers are classified into five categories of technical, legal, economic, sociocultural, and support by help of experts. Then, the fuzzy Best-Worst method is used to determine importance of the identified criteria and sub-criteria for development of the solar energy sector in the region. The findings indicate that the primary barriers to solar energy development are economic factors which are related to the adverse impact of the uncertain economic conditions including the sanctions against Iran. Because of the high risk of new business, domestic people do not have enough ambition and interest in starting new renewable energy projects. The low price of fossil fuels (in the economic category as sub-criteria), has the most significant impact on the stagnation of this sector, which is related to the ease of access to energy in Iran and its effect on the interest in renewable energy use. Supporting the private sectors by receiving financial incentives can help development of the renewable energy sector in the province. By using similar research for other regions, decision makers can accurately identify challenges for development of solar energy.

The electro-osmotically modulated hemodynamic across an artery with multiple stenosis is mathematically evaluated. The non-Newtonian behaviour of blood flow is tackled by utilizing Casson fluid model for this flow problem. The blood flow is confined in such arteries due to the presence of stenosis and this theoretical analysis provides the electro-osmotic effects for blood flow through such arteries. The mathematical equations that govern this flow problem are converted into their dimensionless form by using appropriate transformations and then exact mathematical computations are performed by utilizing Mathematica software. The range of the considered parameters is given as 0 . 03 δ l 0 . 12 , 2 m 3 . 5 , 0 . 03 Q 2 , 0 U HS 3 , 2 B r 2 . 9 , 0 . 01 S 0 . 025 . The graphical results involve combine study of symmetric and non-symmetric structure for multiple stenosis. Joule heating effects are also incorporated in energy equation together with viscous effects. Streamlines are plotted for electro-kinetic parameter m and flow rate Q . The trapping declines in size with incrementing m , for symmetric shape of stenosis. But the size of trapping increases for the non-symmetric case.

To reach the lowest time for discharging process, not only the configuration of tank and material properties but also the external forces can be helpful. Among various approaches, using nanomaterial with wavy wall as well as insertion of Lorentz forces has been examined in current article. Galerkin approach was successfully applied for current modeling and impacts of active factors were exhibited. Direct relation of needed time and A shows that conduction rises with augment of A while the volume of PCM is not changed. Time reduces about 6.96% with rise of A in presence of Ha. Providing greater conduction mode with rise of Ha must be helpful to decline the need time. At A = 0.1, m = 5.7, augmentation of Ha from 0 to 20 leads to decline the time from 250.7 s to 247 s. At Ha = 20, A = 0.3, required time changes from 250.7 s to 229.8 s with rise of m. This behavior is due to higher knf of platelet shape. Rise of time augment the solid fraction but energy stored reduces.

This paper considered the behavior of an incompressible fluid, sediment and solid particles debris at the time of a dam break. This process was studied numerically on the basis of three-dimensional Reynolds-averaged Navier-Stokes equations in combination with the k-ω turbulence model. The VOF (Volume of Fluid) method was used to simulate the fluid and sediment. In order to simulate the movement of water and sediment, a combination of Newtonian and non-Newtonian models was carried out. The effect of water flow on the transport of solid particles and moving sediments is also considered. In order to be convinced of the effectiveness and reliability of the model, the numerical results were compared with experimental data and with calculated data performed by other authors. Further, a proven mathematical model is applied to numerically simulate the movement of fluid behind the dam during the break of the dam body with a riverbed landscape, taking into account multi-level protection. The pressure that the water flow exerts on the additional dam in downstream in the case of cylindrical columns and without them was calculated. Since the columns block the path of solid particles, the pressure exerted on the additional dam is noticeably reduced, and in this case it can be assumed that a potential dam break will not occur, and if it does, then with the least damage. This configuration imitates a robust multi-level protection system that can be used to prevent the serious consequences of a dam failure.

To demonstrate the behavior of hybrid nanofluid in existence of MHD impact, new approach has been examined. Contours and 3D plots were two kinds of outcomes which present the variation of scrutinized variables. Selecting hybrid nanomaterial as testing fluid is owing to reduction of entropy with mixing of nanoparticles. The growth of permeability leads to higher nanomaterial velocity while entropy generation declines. To achieve lower Bejan number, strength of magnetic field should be declined. The growth of Ha (Hartmann) increases exergy destruction and force the thermal plume to vanish. At log(Ra) = 3, Da = 0.01, growth of Ha leads to 1.53% and 0.095% augmentation in Xd and Be, respectively while Nu declines about 0.24%. Augment of Da makes Nu to augments about 1.44% while Be and Xd reduces about 1.4% and 0.095%, respectively. Strength of vortex enhances about 60% with rise of permeability while it decreases about 37.5% with augment of Ha. Ψ for higher Ra is 18.46% higher than that of lowest Ra. Temperature of element reduces about 19.04% and 54% with rise of Da and Ra but it augments about 29.4% with increase of Lorentz term.

In this paper, a mathematical model has been developed that describes the characteristics of fluid flow and dispersion of pollutants in a certain quarter of Almaty city, Kazakhstan. The influence of traffic tidal flow was investigated based on the results of passing vehicles measurements as a source of pollution by the CFD method and on the spatial distribution of pollutants for different types of pollution. To validate the numerical algorithm and mathematical model, a test problem was performed. The RNG k-e turbulence model was used as a turbulent model. The obtained data were compared with the measured and calculated values. After validation of the mathematical model, the main problem was characterized: the pollutant emissions process between houses using different types of pollution sources and the presence of different heights of barriers. The calculated data were compared with the obtained calculated values. In the course of various studies, it has been found that, despite different types of pollutants, the presence of barriers along the road reduces the concentration of harmful substances in the pedestrian zone air. And also the optimal height of this barrier along the road was chosen for maximum protection of the pedestrian part from harmful pollutants. And it was found that when using a barrier with a height of 3 m, the concentration value drops more than two times, as opposed to without a barrier, and a further increase in height is not economically profitable and does not give the desired results.

Numerical simulation of hybrid nanomaterial free convection with helps of CVFEM was performed. Dispersing nanomaterial can minimize the exergy loss. The modeling outputs were depicted in terms of 3D plots and contours. Because of reduction of irreversibility with inclusion of nanoparticles, hybrid nanofluid was employed. Increasing Ha results in greater Xd and it is more sensible when convection become stronger. The growth of permeability increases nanomaterial motion and reduces the exergy drop.

To manage the convective flow through a permeable geometry, Lorentz and gravity forces were applied in this simulation. In equations of velocity, permeability and MHD effects as well as gravity force have been involved. To calculate the values of scalars, CVFEM was employed for last form of equations which were achieved with incorporating Ω. Testing fluid within the enclosure is hybrid nanomaterial and for predicting its features, single phase approach was utilized. Higher values of Ra and Da makes convective flow to increase, while Lorentz forces make the conduction mode to increase and reduce the velocity of carrier fluid. Temperature of elliptic surface augments about 14.2% and 25% with rise of K and buoyancy but it augments about 7.14%. Sgen,th decreases about 22.2% with rise of Ra. Sgen,f reduces by 33% with growth of Da. Amounts of Be augment about 11.33% and 3.47% with growth of Ha and Da, while augment for Ra leads to reduction of Be about 67.92%. Nu decreases about 26.15% with augment of Ha, while rise of Da makes Nu to increase about 12.32%.Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.okAuthor names: Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Also, kindly confirm the details in the metadata are correct.ok

Observing the growing energy demand of modern societies, many countries have recognized energy security as a looming problem and renewable energies as a solution to this issue. Renewable hydrogen production is an excellent method for the storage and transfer of energy generated by intermittent renewable sources such as wind and solar so that they can be used at a place and time of our choosing. In this study, the suitability of 15 cities in Fars province, Iran, for renewable hydrogen production was investigated and compared by the use of multiple multi-criteria decision-making methods including ARAS, SAW, CODAS, and TOPSIS. The obtained rankings were aggregated by rank averaging, Borda method, and Copeland method. Finally, the partially ordered set ranking technique was used to reach a general consensus about the ranking. The criteria that affect hydrogen production were found to be solar energy potential, wind energy potential, population, air temperature, natural disasters, altitude, relative humidity, land cost, skilled labor, infrastructure, topographic condition, and distance from main roads. These criteria were weighted using the best–worst method (BWM) based on the data collected by a questionnaire. Solar energy potential was estimated using the Angstrom model. Wind energy potential was estimated by using the Weibull distribution function for each month independently. The results of the multi-criteria decision-making methods showed Izadkhast to be the most suitable location for renewable hydrogen production in the studied area.

To detect the influence of MHD on migration of hybrid nanopowders, CVFEM has been employed in this paper. Mixture of Fe3O4 and MWCNT was added in water and for calculating properties, experimental formulas were utilized. To increase the convective mode, porous media has been used and tank was experienced in the horizontal magnetic field. In governing equations, there exist two new terms, one for permeable media and the other for MHD effect. Such complex physics needs special numerical approach and CVFEM has been utilized for this goal. Final formulation of PDEs did not have pressure terms and the stream function scalar was introduced. As permeability of zone enhances, nanopowders can transfer faster and the interaction of them with wall enhances, so, Nusselt number augments as well as stream function. Besides, employing higher Ha, the force against the buoyancy force increases and the velocity of operating fluid declines which provides lower convective flow. With rise of Ha, stream function declines about 48% and Nu declines about 31.92% when [Formula: see text]. As Da rises, Nu rises about 33.43% when [Formula: see text]. Augment of Rd leads to augmentation of Nu.

The objective of the current paper is to study the two-dimensional, incompressible nanofluid flow over a curved stretching sheet coiled in a circle. Further, the impact of dispersion of nanoparticle CuO in base liquid water on the performance of flow, thermal conductivity and mass transfer using KKL model in the presence of Cattaneo-Christov heat flux and activation energy is deliberated. A curvilinear coordinate system is used to develop the mathematical model describing the flow phenomena in the form of partial differential equations. Further, by means of apt similarity transformations the governing boundary value problems are reduced to ordinary differential equations. Mathematical computations are simplified using Runge-Kutta-Fehlberg-45(RKF-45) process by adopting shooting method. Graphical illustrations of velocity, temperature, concentration gradients for various pertinent parameters are presented. The result reveals that, the heightening of porosity parameter heightens the thermal gradient but converse trend is depicted in velocity gradient. The enhancing values of Schmidt number and chemical reaction rate parameter declines concentration gradient whereas converse trend is depicted for upsurge in activation energy parameter.

In current context, turbulent flow with install of helical tape has been analyzed in a system in which nanofluid was utilized in shell side. Both hydrothermal and exergy analysis are presented. Hot gas and H2O-CuO nanofluid are considered as working fluids. FVM is utilized to explore the roles of Re, number of revolution (N) on hydrothermal treatment. Suitable correlations for entropy components are extracted according to obtained data. Radial velocity can be augmented with enhance of revolution and inlet velocity of nanofluid. So, friction augments and higher values of pressure drop can be achieved. Augment of revolution leads to augmentation of pressure loss about 95.25% and 81.42% depend on the values of Re. When revolution has highest value, pressure drop faces 389.4% augmentation with rise of Re. With assuming largest amounts of other variables, growth of Re makes outlet temperature to reduce about 8.4% while rise of N results in 0.73% augmentation in Tout. Assuming N=7, augment of Re leads to decline Xd by 64.29%. At Re⁎=5, growth of N up to 7 makes Xd to reduce about 62.43%.

Worldwide energy supply is mostly reliant on fossil fuels. Carbon dioxide emissions have caused many negative environmental issues like climate change, air pollution, and energy security. An important alternative to this hazard is substituting the fossil fuel-based carbon energy sources with renewable energy sources. Passive strategies, which are devised to provide thermal comfort in buildings are examples of how to use renewable energies. For this study, a dairy product warehouse in the city of Yazd in Iran was thoroughly investigated. The main goal of this study is to introduce different scenarios, then identifying them based upon optimization of energy consumption. Another main purpose of the present study is to maximize the use of passive energy to meet the cooling needs of a dairy products warehouse in the studied area. Underground temperature is lower than the surface in summer, also it is higher in winter. Therefore, this property of soil is investigated by using nine different scenarios at different heights for constructing underground warehouse for storing dairy products. Clearly, different renewable tools like wind turbine, wind catcher, solar chiller, and different roof designs by Savanah grass, roof pond are also investigated. At first, the cooling load of the warehouse is calculated separately for each season. Then, according to the energy load values obtained, the nominated scenarios are investigated. The results of the comparisons show that the construction of a warehouse at a depth of 3 m from the ground with a green roof covered with Savannah grass helps achieve the best degree of reduction in the cooling power.

Nanofluids manage heat in the internal combustion of the engines or machines by avoiding corrosion in the cooling system as well as assist in eradicating the engine’s waste heat. Hence, they are used as coolants in many automotive industries. Inspired by these applications, the thermal and mass transfer in hybrid nanoliquid flow over a stretching cylinder on taking account of magnetic dipole is studied in this investigation. Here, we have done a comparative study on flow of two diverse combinations of hybrid nanofluids, namely MnZnFe 2 O 4 − NiZnFe 2 O 4 − C 10 H 22 and Cu − Al 2 O 3 − C 10 H 22 . The modelled equation for the assumed flow is converted to ODEs by opting appropriate similarity variables. These ODEs are solved by utilizing the Runge–Kutta Fehlberg fourth-fifth order (RKF-45) method by adopting shooting technique. Physical clarification of relevant parameters for non-dimensional discrete flow fields are discussed briefly by using graphs. Also, skin friction, Sherwood and Nusselt numbers are deliberated with the assistance of graphs. Results reveal that, the upsurge in ferromagnetic interaction parameter declines the velocity in both fluids but converse trend is detected in temperature and concentration of the liquids. The heightening of ferromagnetic interaction parameter declines the rate of heat and mass transfer.

In this paper, we study the gravitational collapse of a spherical symmetric star constituted of matter interacting with vacuum energy density [Formula: see text] in the background of spacetime curvature. We consider the gravitational collapse for closed, flat, and hyperbolic spacetime geometry [Formula: see text]. We take the process of gravitational collapse for an anisotropic fluid interacting with a growing vacuum energy density by taking a complete physically general-relativistic approach in the background of spacetime curvature. Here, we achieved analytic solutions with some assumptions of physical significance. We executed and interpreted the solutions for several cases of the equation of state parameters, [Formula: see text]. In all physical cases, we investigate the formation of a black hole and the naked singularity.

The research on flow of fluids fuelled by rotating disk motion has been increasing, due to the development of machine technology. Inspired by this development, we examined the deposition of thermophoretic particles in the flow of hybrid nanofluid suspended by ferrite nanoparticles past an expansion/contraction moving disk with rotation. Estimated PDE's are converted to ODEs with consideration of the corresponding similarity transformations. The obtained nondimensional expressions are solved by a numerical process known as the Runge-Kutta Fehlberg fourth - fifth order (RKF-45 method) by adopting shooting technique. Behavioural studies of velocity, concentration and thermal profiles of various parameter values are assessed using graphs. Physical concern parameters such as, velocity of thermophoretic particle deposition and velocity of thermophoretic are also analyzed graphically. The result reveals that, speed of the disk movement in the upward direction escalates the tangential as well as radial velocity gradients and rise in values of thermophoretic coefficient and thermophoretic parameter declines the rate of mass transfer.

Water pollution incidents have occurred frequently and have caused serious damage in recent years. The purpose of this study is to create a model for modeling the spatio-temporal water pollution from the activities of industrial facilities. In this study, a water pollution diffusion modeling system was developed. An example is the pollution of the Ilek River in the city of Aktobe, Kazakhstan, where two-dimensional non-stationary numerical modeling is applied with a detailed mechanism of a chemical reaction. The chemical reaction is numerically investigated by solving the equations of mass conservation, momentum and chemical concentration in flow. The results show that pollutants move downstream with an increase in the area of pollution, but with a reduced concentration. In addition, spatio-temporal changes in the concentration of pollutants show a tendency that the concentration in certain regions stagnates, reaching a certain level. It was also revealed in the work that, despite the fact that the emitted element HNO2 does not exceed the threshold limit value (TLV) value, the obtained products from the chemical reaction (HNO3, HCl) exceed the TLV value several times and cause great harm to the flora and fauna of the aquatic environment. Numerical results for two-dimensional mass transfer with a chemical reaction are presented under different river flow conditions. The model provides a reliable tool for detailed investigation of the complex interaction of flow and chemical composition.

This paper presents numerical solutions of the mixed convection in backward-facing step flows with the vertical buoyancy forces. A two-dimensional incompressible Navier-Stokes equation is used to describe this process. This system is approximated by the control volume method and solved numerically by the projection method. The two-dimensional Poisson equation satisfying the discrete continuity equation that is solved by the Jacobi iterative method at each time step. The numerical solutions of the laminar flow behind the backward-facing step with the vertical buoyancy forces are compared with the numerical results of other authors. This numerical algorithm is completely parallelized using various geometric domain decompositions (1D, 2D and 3D). Preliminary theoretical analysis of the various decomposition methods effectiveness of the computational domain and real computational experiments for this problem were made and the best domain decomposition method was determined. In the future, a proven mathematical model and parallelized numerical algorithm with the best domain decomposition method can be applied for various complex flows with the vertical buoyancy forces. G M T Detect language Afrikaans Albanian Arabic Armenian Azerbaijani Basque Belarusian Bengali Bosnian Bulgarian Catalan Cebuano Chichewa Chinese (Simplified) Chinese (Traditional) Croatian Czech Danish Dutch English Esperanto Estonian Filipino Finnish French Galician Georgian German Greek Gujarati Haitian Creole Hausa Hebrew Hindi Hmong Hungarian Icelandic Igbo Indonesian Irish Italian Japanese Javanese Kannada Kazakh Khmer Korean Lao Latin Latvian Lithuanian Macedonian Malagasy Malay Malayalam Maltese Maori Marathi Mongolian Myanmar (Burmese) Nepali Norwegian Persian Polish Portuguese Punjabi Romanian Russian Serbian Sesotho Sinhala Slovak Slovenian Somali Spanish Sundanese Swahili Swedish Tajik Tamil Telugu Thai Turkish Ukrainian Urdu Uzbek Vietnamese Welsh Yiddish Yoruba Zulu Afrikaans Albanian Arabic Armenian Azerbaijani Basque Belarusian Bengali Bosnian Bulgarian Catalan Cebuano Chichewa Chinese (Simplified) Chinese (Traditional) Croatian Czech Danish Dutch English Esperanto Estonian Filipino Finnish French Galician Georgian German Greek Gujarati Haitian Creole Hausa Hebrew Hindi Hmong Hungarian Icelandic Igbo Indonesian Irish Italian Japanese Javanese Kannada Kazakh Khmer Korean Lao Latin Latvian Lithuanian Macedonian Malagasy Malay Malayalam Maltese Maori Marathi Mongolian Myanmar (Burmese) Nepali Norwegian Persian Polish Portuguese Punjabi Romanian Russian Serbian Sesotho Sinhala Slovak Slovenian Somali Spanish Sundanese Swahili Swedish Tajik Tamil Telugu Thai Turkish Ukrainian Urdu Uzbek Vietnamese Welsh Yiddish Yoruba Zulu Text-to-speech function is limited to 200 characters Options : History : Feedback : Donate Close

We presented an unsteady mixture of Casson Micropolar nanofluid flow and heat transfer over a permeable stretching/shrinking channel in the presence of Induced magnetic field and hydrodynamic Lorentz force which acts opposite to the flow and helps control the flow dynamics. Since the geometry of the channel is curved therefore, we employed Curvilinear coordinates to best label the envisaged problem. Mathematical modelling of the flow current resulted in an intricate system of partial differential equations with various embedded parameters. The simplified version of the system of resulting ordinary differential equations is simulated using the MATLAB function bvp4c setting tolerance level at 1e-4. To achieve the desired boundary conditions, the solver is applied recursively to pick the best match of the assorted parameters. Physical significance of sundry parameters used for velocity, induced magnetic, micro-rotational, temperature and concentration profiles are highlighted through graphs and arguments. Curvature of the channel is responsible for slowing down the flow, while significant importance of stretching/shrinking channel is visible as the Non-Newtonian fluid is discharged over the curved channel.

The momentum and thermal boundary layer flow problem for shear thinning fluid with modified viscosity model over moving wedge is discussed. The mathematical model of the problem is developed by using improved Carreau model relates viscosity to shear rate and using the thermal conductivity model in the similar form of viscosity expression. The improved Carreau model contains five-parameters: zero viscosity, high shear rate viscosity, flow behavior index, consistency index and viscosity curvature which cover almost all aspects of the fluid's rheology. On the governing equations of the problem, boundary layer approximations are used and then reduced into ordinary differential equations by using similarity transformations. The results in form of velocity and temperature profiles, thickness of boundary layers regions, deflation in volume and momentum flow rates under the influence of all the parameters are calculated and displayed in graphs and tables for discussion. The effects of zero viscosity on different profiles are dominant as compared to high shear rate viscosity. The velocity is decreased but temperature profile is increased by the parameters that are involved to increase to viscosity.

This research work interprets the mathematical study of peristaltic flow of non-Newtonian fluid across an elliptical duct. The heat transfer mechanism for this elliptical duct problem is also considered in detail. The mathematical equations for Casson fluid model are developed and then by using appropriate transformations and long wavelength approximation, this mathematical problem is converted into its dimensionless form. After converting the problem in dimensionless form, we have obtained partial differential equations for both velocity and temperature profiles. These partial differential equations are solved subject to given boundary conditions over elliptical cross sections and exact mathematical solutions are obtained. The results are further discussed by plotting graphical results for velocity, pressure gradient, temperature, pressure rise and streamlines.

This article discusses the important of single wall carbon nanotube (SWCNTs) and multiple walls carbon nanotube (MWCNTs) past a static wedge under the effects of magnetohydrodynamics (MHD). The significance of activation energy, thermal radiation, heat generation and double stratification are also taken into account. Utilizing the BVP-4c function of MATLAB the system of differential equations is solved numerically. To validate our results, a correlation with a previously studied problem is also directed and a brilliant concurrence is found; thus, reliable results are being introduced. The influence of sundry parameter on axial velocity, temperature, and concentration profile are deliberated and studied graphically. The temperature and concentration distribution diminish respectively with thermal and concentration stratified parameter. Further the solid volume fraction enhances the axial velocity and temperature profile for both carbon nanotubes.

In this paper, the effects of water on obstacles in the dam break flow problem are investigated numerically. The numerical method is based on the Navier-Stokes equations describing the flow of an incompressible viscous fluid and the equation for the phase. As a numerical method for solving equations, the numerical algorithm PISO was chosen. The water surface movement is captured by using the volume of fluid (VOF) method, which leads to a strict mass conservation. Moreover the accuracy and reliability of the 3D model were tested using large-scale laboratory experiments on dam destruction problem. The obtained free surface dynamics was compared with the experimental data and numerical results of other authors. These numerical results gave good agreement with the experimental data. By dam break flow problem simulation, the best turbulent models were chosen, which describe almost the same pressure distribution as in the experiment. Finally, various forms of obstacles were examined, by which the pressure distributions were reduced three times on the dam surface.

This paper presents computational fluid dynamics (CFD) techniques in modeling the pollution distribution from thermal power plant. Carbon dioxide (\(CO_{2}\)) dispersion from a thermal power plant was simulated. The mathematical model and numerical algorithm were tested using a test problem and gave a good match with the experimental data. The influence of gravity force was taken into account. The k-epsilon model of turbulence with the buoyancy force was used. Calculations were performed by ANSYS Fluent. As a result, there was found a distance from the source at which the impurity settles on the ground surface.

Taking into account the high rate of construction in the modern big cities, it is very important to save the natural aerodynamics between the buildings. It is necessary to explore the ventilation of space between architectural structures, making a preliminary prediction before construction starting. The most optimal way of evaluating is to build a mathematical model of air flow. This paper presents numerical solutions of the wind flow around the architectural obstacles with the vertical buoyancy forces. An incompressible Navier-Stokes equation is used to describe this process. This system is approximated by the control volume method and solved numerically by the projection method. The Poisson equation that is satisfying the discrete continuity equation solved by the Jacobi iterative method at each time step. For check correctness of mathematical model and numerical algorithm is solved test problem. The numerical solutions of the backward-facing step flow with the vertical buoyancy forces, which was compared with the numerical results of other authors. This numerical algorithm is completely parallelized using various geometric domain decompositions (1D, 2D and 3D). Preliminary theoretical analysis of the various decomposition methods effectiveness of the computational domain and real computational experiments for this problem were made and the best domain decomposition method was determined. In the future, a proven mathematical model and parallelized numerical algorithm with the best domain decomposition method can be applied for various complex flows with the vertical buoyancy forces.

Thermal pollution of water bodies is an inevitable consequence of a power plant operation. To minimize the harmful effects, it is necessary to evaluate the different locations for the heated water discharge from the power plant. The most effective approach to solving these problems is a computational experiment. In this paper, the numerical studies of thermal pollution of the Irtysh River as a natural water cooling system from the power plant operation were presented. And studies were conducted to study thermal pollution under different scenarios, the impact of the heated water discharge from a power plant into the Irtysh River.

This analysis comprises the innovative technique to analyze the bifurcation of streamlines by considering the model of shear thinning fluid inside the channel as well as through tube of axisymmetric tube. The set of the equations governing the flow model are transformed into differential equations by approximations prior to pursuing the analytical solutions for particle paths. The methodology of dynamical systems is used to inspect the local bifurcation and change observed in their topologies. When sundry parameters take definite degenerate values the phenomenon of bifurcation occurs. Three distinct flow situations like augmented, trapping and backward appear due to transition. The global bifurcation plots summarized all these bifurcation. The topological changes in plots of bifurcation are inspected via graphs.

The paper presents a mathematical model of the thermal load on the aquatic environment under various operational capacities of thermal power plant. It is solved by the Navier–Stokes and temperature equations for an incompressible fluid in a stratified medium based on the splitting method by physical parameters which approximated by the finite volume method. The numerical solution of the equation system is divided into four stages. At the first step it is assumed that the momentum transfer carried out only by convection and diffusion. Intermediate velocity field is solved by five-step Runge–Kutta method. At the second stage, the pressure field is solved by the found intermediate velocity field. Poisson equation for the pressure field is solved by Jacobi method. The third step assumes that the transfer is carried out only by pressure gradient. The fourth step of the temperature equation is also solved as motion equations, with five-step Runge–Kutta method. The algorithm is parallelized on high-performance computer. The obtained numerical results of three-dimensional stratified turbulent flow were compared with experimental data. What revealed qualitatively and quantitatively approximately the basic laws of hydrothermal processes occurring in the reservoir-cooler.

The paper presents a mathematical model of the thermal load on the aquatic environment under operational capacity 200 MW of thermal power plant. It is solved by the Navier–Stokes and temperature equations for an incompressible fluid in a stratified medium based on numerical method, the splitting method by physical parameters which approximated the finite volume method. The numerical solution of the equation system is divided into four stages. At the first step it is assumed that the momentum transfer is carried out only by convection and diffusion. Intermediate velocity field is solved by the five-step Runge–Kutta method. At the second stage, the pressure field is solved by the intermediate velocity field. Poisson equation for the pressure field is solved by Jacobi method. The third step is assumed that the transfer is carried out only by pressure gradient. The fourth step of the transport equation for temperature is also solved as momentum equations, with five-step Runge–Kutta method. The obtained numerical results of temperature distribution for operational capacity of 200 MW of three-dimensional stratified turbulent flow were compared with experimental data, which revealed qualitatively and quantitatively approximately the basic laws of hydrothermal processes occurring in the reservoir-cooler.

This paper considers the unstable stratified turbulent flow in an open channel. A mathematical model of unstable stratified turbulent flow is introduced, which allows to assess the mean and fluctuation characteristics of the turbulent flow. The numerical algorithm is developed for solving this problem. A numerical method is based on the projection method, which divides the problem into three stages. At the first stage, it is assumed that the transfer of momentum occurs only by convection and diffusion. Intermediate velocity field is solved by fractional steps method. At the second stage, three-dimensional Poisson equation is solved by the Fourier method in combination with tridiagonal matrix method (Thomas algorithm). Finally, at the third stage, it is expected that the transfer is only due to the pressure gradient. The simulation results are in satisfactory agreement with the experimental data.

The use of parallel computing technologies for numerical simulation of air transport in the human nasal cavity was considered in this paper. Investigation of air flow in the human nasal cavity is of considerable interest, since breathing is done mainly through the nose. A two-dimensional numerical simulation of air transport in the model cross-sections of the nasal cavity to normal human nose based on the Navier-Stokes equations, the equations for temperature and equation for relative humidity were conducted in this study. The projection method is used for the numerical solution of this system of equations. This numerical algorithm was fully parallelized using different geometric decompositions (1D, 2D, and 3D). A preliminary theoretical analysis of the speed-up and effectiveness of various methods of decomposition of the computational domain and the real numerical experiments for this problem were made in this work. Moreover the best domain decomposition method has been determined. The obtained data transfer numerical modelling air human nasal cavity was verified with known numerical results in the form of velocity and temperature profiles.

The article focuses on the mixed convective flow of Ag–ethylene glycol nanofluid. The analysis is carried out for a cavity having center as heated. The relatively moving side walls of cavity are retained at low constant temperature while constant heat source is examined in the bottom wall. The rest of the bottom and top walls remain insulated. Cattaneo–Christov heat flux is implemented in the analysis of heat transfer. Heat transfer rate is dig out for the case of Fourier’s heat flux, as for the case of Cattaneo–Christov heat flux it gives implicit expression, which is difficult to analyze and simplify. The problem is analyzed numerically via projection method. Higher heat transfer is observed for the Fourier’s law as compare to Cattaneo–Christov heat flux. The results are expressed by isotherms, streamlines, velocity field, and average Nusselt numbers.

The performance of friction drag, heat transfer rate, and mass transfer is illustrated the in boundary layer flow region via density of motile microorganisms. Magnetic dipole in presence of Curie temperature and density of motile microorganisms plays important role in stabilizing and controlling the momentum and thermal boundary layers. In this direction, the characteristics of the magnetic dipole on the suspensions of motile microorganisms in the flow of ferrofluid are incorporated. Heat flux in the suspensions of motile microorganisms and at the surface is computed via Fourier's law of heat conduction. Characteristics of sundry physical parameter on the ferrohydrodynamic, thermal energy, mass transfer, and bioconvection are computed numerically and analytically. It is depicted that an enhancement in thermal Rayleigh number results in the reduction of friction drag, thereby enhances the heat transfer rate and Sherwood number at the surface, while the local density of motile microorganisms enhance for larger values of bioconvection Lewis number. Further, it is characterized that bioconvection Rayleigh number has increasing behavior on the heat transfer in the boundary layer. Comparison with available results are found in an excellent agreement.

Zonal RANS/LES modelings have received considerable attention over recent years. Especially with the?attached boundary layers that computed using the Reynolds-averaged Navier – Stokes (RANS) equations, and non-equilibrium zones of the flow by large-eddy simulation (LES). Generation eddies from a smooth RANS field of turbulent eddies capable of supporting the Reynolds stresses in the LES zones are one issue that may affect the accuracy of the results of zonal methods. Synthetic turbulence and controlled forcing are used to generate turbulence structures in the LES zones.

This paper presents the mathematical model of the thermal influence to the aquatic environment of thermal power plant, which is solved by the Navier-Stokes and temperature equations for an incompressible fluid in a stratified medium. Numerical algorithm based on the projection method which solved with fractional step method. Three dimensional Poisson equation solved with Fourier method with combination of tridiagonal matrix method (Thomas algorithm).

The active development of the industry leads to an increase in the number of factories, plants, thermal power plants, nuclear power plants, thereby increasing the amount of emissions into the atmosphere. Harmful chemicals are deposited on the soil surface, remain in the atmosphere, which leads to a variety of environmental problems which are harmful for human health and the environment, flora and fauna. Considering the above problems, it is very important to control the emissions to keep them at an acceptable level for the environment. In order to do that it is necessary to investigate the spread of harmful emissions. The best way to assess it is the creating numerical simulation of gaseous substances’ motion. In the present work the numerical simulation of the spreading of emissions from the thermal power plant chimney is considered. The model takes into account the physical properties of the emitted substances and allows to calculate the distribution of the mass fractions, depending on the wind velocity...

The paper presents a numerical modelling of the thermal load on the aquatic environment by using two water discharge pipes of the thermal power plant. It is solved by the Navier-Stokes and temperature transport equations for an incompressible fluid in a stratified medium. The numerical solution of the equation system is divided into four stages by using projection method which was approximated by the finite volume method. At the first step it is assumed that the momentum transfer was carried out only by convection and diffusion. Intermediate velocity field is solved by 5-step Runge-Kutta method. At the second stage, the pressure field is solved by found the intermediate velocity field. Poisson equation for the pressure field is solved by Jacobi method. The third step is assumed that the transfer is carried out only by pressure gradient. The fourth step of the temperature transport equation is also solved as momentum equations. The obtained numerical results of stratified turbulent flow for two water discharged pipes were compared with experimental data and with numerical results for one water discharged pipe. General thermal load in the reservoir-cooler decreases comparing one water discharged pipe and revealed qualitatively and quantitatively approximately the basic laws of hydrothermal processes occurring in the reservoir-cooler can be seen that from numerical simulations where two water discharged pipes were used.

In the research the numerical simulation of the room’s ventilation was performed on the basis of the large eddy simulation. The numerical algorithm was developed by using the physical parameters splitting scheme. Poisson equation for pressure field is solved by Fourier method in combination with tridiagonal matrix method for determination of Fourier coefficients. The parallel programming technique MPI in combination with directives of OpenMP was applied to solve the assign task, as the most relevant for today and the most efficient a view of the productivity improvement of complex calculations. Simulation data are represented as three-dimensional graphs.

Parallel implementation of algorithm of numerical solution of Navier-Stokes equations for large eddy simulation (LES) of turbulence is presented in this research. The Dynamic Smagorinsky model is applied for sub-grid simulation of turbulence. The numerical algorithm was worked out using a scheme of splitting on physical parameters. At the first stage it is supposed that carrying over movement amount takes place only due to convection and diffusion. Intermediate field of velocity is determined by method of fractional steps by using Thomas algorithm (tridiaginal matrix algorithm). At the second stage found intermediate field of velocity is used for determination of the field of pressure. Three dimensional Poisson equation for the field of pressure is solved using upper relaxation method. Moreover various ways of geometrical decomposition for parallel numerical solution of three dimensional Poisson equations are investigated.