Mechanism of Thermally Radiative Prandtl Nanofluids and Double-Diffusive Convection in Tapered Channel on Peristaltic Flow with Viscous Dissipation and Induced Magnetic Field

The application of mathematical modeling to biological fluids is of utmost importance, as it has diverse applicationsin medicine. The peristaltic mechanism plays a crucial role in understanding numerous biological flows. In thispaper, we present a theoretical investigation of the double diffusion convection in the peristaltic transport of aPrandtl nanofluid through an asymmetric tapered channel under the combined action of thermal radiation andan induced magnetic field. The equations for the current flow scenario are developed, incorporating relevantassumptions, and considering the effect of viscous dissipation. The impact of thermal radiation and doublediffusion on public health is of particular interest. For instance, infrared radiation techniques have been used totreat various skin-related diseases and can also be employed as a measure of thermotherapy for some bones toenhance blood circulation, with radiation increasing blood flow by approximately 80%. To solve the governingequations, we employ a numerical method with the aid of symbolic software such as Mathematica and MATLAB.The velocity, magnetic force function, pressure rise, temperature, solute (species) concentration, and nanoparticlevolume fraction profiles are analytically derived and graphically displayed. The results outcomes are compared withthe findings of limiting situations for verification.

Three-dimensional stretched flow of Jeffrey fluid with variable thermal conductivity and thermal radiation

This article addresses the three-dimensional stretched flow of the Jeffrey fluid with thermal radiation. The thermal conductivity of the fluid varies linearly with respect to temperature. Computations are performed for the velocity and temperature fields. Graphs for the velocity and temperature are plotted to examine the behaviors with different parameters. Numerical values of the local Nusselt number are presented and discussed. The present results are compared with the existing limiting solutions, showing good agreement with each other.

MHD three dimensional flow of viscoelastic fluid with thermal radiation and variable thermal conductivity

The objective of the present work is to model the magnetohydrodynamic(MHD) three dimensional flow of viscoelastic fluid passing a stretching surface. Heat transfer analysis is carried out in the presence of variable thermal conductivity and thermal radiation. Arising nonlinear analysis for velocity and temperature is computed. Discussion to importantly involved parameters through plots is presented. Comparison between present and previous limiting solutions is shown. Numerical values of local Nusselt number are computed and analyzed. It can be observed that the effects of viscoelastic parameter and Hartman number on the temperature profile are similar in a qualitative way. The variations in temperature are more pronounced for viscoelastic parameter K in comparison to the Hartman number M. The parameters N and ε give rise to the temperature. It is interesting to note that values of local Nusselt number are smaller for the larger values of ε.

Three-dimensional flow of Powell–Eyring nanofluid with heat and mass flux boundary conditions

This article investigates the three-dimensional flow of Powell–Eyring nanofluid with thermophoresis and Brownian motion effects. The energy equation is considered in the presence of thermal radiation. The heat and mass flux conditions are taken into account. Mathematical formulation is carried out through the boundary layer approach. The governing partial differential equations are transformed into the nonlinear ordinary differential equations through suitable variables. The resulting nonlinear ordinary differential equations have been solved for the series solutions. Effects of emerging physical parameters on the temperature and nanoparticles concentration are plotted and discussed. Numerical values of local Nusselt and Sherwood numbers are computed and examined.

Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber

Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.

A three-dimensional model for the transportation of Fe and Mn in Arha Reservoir

Coupling with a three dimensional (3D) hydrodynamic model and a suspended solids model, a 3D model for the transport of Fe and Mn in Arha Reservoir, China, was developed. The 3D velocity fields for the flood season are computed to drive the 3D model of Fe and Mn in which the processes of advection, diffusion, redox, sorption, desorption, deposition, and re suspension are included. The model has been calibrated by matching observed fluid, suspended solids, and total concentrations of Fe and Mn in the water column and in the sediment, successively. The model simulated both horizontal and vertical gradients of Fe and Mn in Arha Reservoir. It was found that Fe and especially Mn stratify in accordance with the stratification of DO during summer. The redox cycles across the water sediment interface has a principal role in the rise of Fe and Mn concentrations in the overlying water. It was also found that Fe and Mn loadings from the tributaries have a carryover effect on the water quality through a secondary contamination in the reservoir.

Flow Field and Thermal Analysis of the Divertor Target Plate for HL-2A Tokamak

In the initial phase of the physics experiment, the double-null divertor plates used consist of graphite armor tiles, Mo-alloy intermediate layers and Cu-alloy coolant tubes. In the later operating phase, tungsten will be used as armor tiles. A multi-physical field numerical analysis method is used in this paper. Its analysis model reflects more realistically the real divertor structure than other models. Two-dimensional （2D） and three-dimensional （3D） fluid flow field, temperature distribution and thermal stress analyses of the divertor plates are carried out by the ANSYS code. During the physics experimental phase with a heat flux of 1 MW/m2, a coolant velocity of 5.48 m/s, and a thermal stress of 750 kg/cm2, the graphite armor tiles successfully meet the requirements of temperature, thermal stress and sputtering erosion. The tungsten armor will be considered as a second candidate. The result of simulation can be used for upgrading the design parameters of the HL-2A poloidal divertor.

EXPERIMENTAL INVESTIGATION FOR THE EFFECT OF ROTATION ON THREE-DIMENSIONAL FLOW FIELD IN FILM-COOLED TURBINE

An experimental investigation of three-dimensional flow field in a film-cooled turbine model is carried out by using particle image velocimeter （PIV） in a low-speed wind tunnel. The effects of different blowing ratios （M=1.5, 2） on the flow field are studied. The experimental results reveal the classical phenomena of the formation of kidney vortex pair and secondary flow in wake region behind the jet hole. And the changes of the kidney vortex pair and the wake at different locations away from the hole on the suction and pressure sides are also studied. Compared with the flow field in stationary cascade, there are centrifugal force and Coriolis force existing in the flow field of rotating turbine, and these forces bring the radial velocity in the jet flow. The effect of rotatien on the flow field of the pressure side is more distinct than that on the suction side from the measured flow fields in Y-Z plane and radial velocity contours. The increase of blowing ratio makes the kidney vortex pair and the secondary flow in the wake region stronger and makes the range of the wake region enlarged.

Thermal Radiation Effect on the MHD Turbulent Compressible Boundary Layer Flow with Adverse Pressure Gradient, Heat Transfer and Local Suction

The combined effect of magnetic field, thermal radiation and local suction on the steady turbulent compressible boundary layer flow with adverse pressure gradient is numerically studied. The magnetic field is constant and applied transversely to the direction of the flow. The fluid is subjected to a localized suction and is considered as a radiative optically thin gray fluid. The Reynolds Averaged Boundary Layer (RABL) equations with appropriate boundary conditions are transformed using the compressible Falkner Skan transformation. The nonlinear and coupled system of partial differential equations (PDEs) is solved using the Keller box method. For the eddy-kinematic viscosity the Baldwin Lomax turbulent model and for the turbulent Prandtl number the extended Kays Crawford model are used. The numerical results show that the flow field can be controlled by the combined effect of the applied magnetic field, thermal radiation, and localized suction, moving the separation point, xs , downstream towards the plate’s end, and increasing total drag, D . The combined effect of thermal radiation and magnetic field has a cooling effect on the fluid at the wall vicinity. The combined effect has a greater influence in the case of high free-stream temperature.

Study on short－range numerical forecasting of ocean current in the East China Sea—II．Three－dimensional diagnostic model and its application in the Bohai Sea

In this paper,a tbree-dimensional (3-D) baroclinic diagnostic model for short-range numerical forecast is proposed to calculate the monthly averaged flow field in the Bohai Sea. By using the model and monthly averaged tempeature and salinity date, monthly barotropic and baroclinic flow field are calculated,and 2-D and 3-D characteristics of flow are described and demonstrated. On the basis of the analysis of the modelling results and the observed temperature,salinity and wind data,the monthly and seasonal characteristics and generation mechanism of circulation in the Bohai Sea are also discussed. It is pointed out in this paper that in spring and autumn,the monthly averaged flow fields are not representative, for the wind direction varies in a wide range and the averaged wind field is much weaker than the instantaneous one. These results show the reliability of the model for describing the monthly characteristics in numerical forecast of ocean current.

Present Geothermal Fields of the Dongpu Sag in the Bohai Bay Basin

The Dongpu sag is located in the south of the Bohai Bay basin,China,and has abundant oil and gas reserves.To date,there has been no systematic documentation of its geothermal fields.This study measured the rock thermal conductivity of 324 cores from 47 wells,and calculated rock thermal conductivity for different formations.The geothermal gradient and terrestrial heat flow were calculated for 192 wells on basis of 892 formation-testing data from 523 wells.The results show that the Dongpu sag is characterized by a medium-temperature geothermal field between stable and active tectonic areas,with an average geothermal gradient of 32.0℃/km and terrestrial heat flow of 65.6 mW/m2.The geothermal fields in the Dongpu sag is significantly controlled by the Changyuan,Yellow River,and Lanliao basement faults.They developed in the Paleogene and the Dongying movement occurred at the Dongying Formation depositional period.The geothermal fields distribution has a similar characteristic to the tectonic framework of the Dongpu sag,namely two subsags,one uplift,one steep slope and one gentle slope.The oil and gas distribution is closely associated with the present geothermal fields.The work may provide constraints for reconstructing the thermal history and modeling source rock maturation evolution in the Dongpu sag.

Numerical simulation of the dimensional transformation of atomization in a supersonic aerodynamic atomization dust-removing nozzle based on transonic speed compressible flow

To simulate the transonic atomization jet process in Laval nozzles,to test the law of droplet atomization and distribution,to find a method of supersonic atomization for dust-removing nozzles,and to improve nozzle efficiency,the finite element method has been used in this study based on the COMSOL computational fluid dynamics module.The study results showed that the process cannot be realized alone under the two-dimensional axisymmetric,three-dimensional and three-dimensional symmetric models,but it can be calculated with the transformation dimension method,which uses the parameter equations generated from the two-dimensional axisymmetric flow field data of the three-dimensional model.The visualization of this complex process,which is difficult to measure and analyze experimentally,was realized in this study.The physical process,macro phenomena and particle distribution of supersonic atomization are analyzed in combination with this simulation.The rationality of the simulation was verified by experiments.A new method for the study of the atomization process and the exploration of its mechanism in a compressible transonic speed flow field based on the Laval nozzle has been provided,and a numerical platform for the study of supersonic atomization dust removal has been established.

SOLITON-LIKE THERMAL SOURCE FORCING AND SINGULAR RESPONSE OF ATMOSPHERE AND OCEANS TO IT

Nonlinear dynamic study is undertaken of the response of atmospheric and oceanic flow fields to local thermal source forcing in the context of a generalized geophysical fluid dynamic barotropic quasi_geostrophic model, discovering a good relation between thermal disturbance and flow field response to it, both having similar modes, and that the soliton_like responding field is a great deal larger in extent than the analogous_form forcing field, which implies that a 'narrow' thermal disturbance can excite a 'wide' response field, in some cases the particular structure of a thermal source may give rise to singular response of atmospheric and oceanic flow fields, thus displaying their abnormalities (for example the blocking situation in the atmosphere), the atmospheric and oceanic stream fields at mid_high latitudes respond to thermal forcing in a much more pronounced manner compared to those at low latitudes. The said research results that is in agreement with studies from mid_low latitude atmospheric experiments and observations and can be used to partially interpret the circulation singularity due to heat source anomaly on a local basis in the context of earch fluid flows.

Thermal Lithospheric Thickness of the Sichuan Basin and its Geological Implications

Thermal lithospheric thickness is an important parameter in studying the tectonic-thermal evolution of basins and plate dynamics.Based on the measured geothermal data and thermophysical properties of the rocks,the thermal lithospheric thickness of the Sichuan Basin was calculated according to the principles of heat conduction in the crust and lithospheric mantle.The calculation results revealed that the thickness of the thermal lithosphere in the Sichuan Basin is 140-190 km and is unevenly distributed.The thickness of the thermal lithosphere in central Sichuan and southwestern Sichuan is less than 160 km,while that in the western Sichuan depression and eastern Sichuan is larger(~180 km).The distribution of the thermal lithospheric thickness in the basin has a good correlation with the geological units and the thickness of the sedimentary layers.The thickness of the thermal lithosphere in the depression area,which has thick sedimentary layers and the fault-fold zone with shallow crustal deformation and thickening,are larger than that in the basement uplifted area,which has thin sedimentary layers.The calculated thermal lithospheric thickness is in good agreement with the geophysical data and reflects the stable conduction temperature field in the Sichuan Basin.The present thermal regime and thermal lithospheric thickness of the Sichuan Basin indicate that flexural thickening of the lithosphere occurred in the eastern Sichuan fault-fold belt and the Longmen Mountain-Western Sichuan depression foreland basin system,while asthenospheric uplift occurred in the central Sichuan region,which were the result of the expansion of the Xuefeng orogeny from the east and the compression of the Tibetan Plateau from the west.

Characteristic size research of human nasal cavity and the respiratory airflow CFD analysis

To study the airflow distribution in human nasal cavity during respiration and the characteristic parameters for nasal structure, thirty three-dimensional, anatomically accurate representations of adult nasal cavity models were reconstructed based on processed tomography images collected from normal people. The airflow fields in nasal cavities were simulated using the fluid dynamics with the finite element software ANSYS. The results showed that the difference of human nasal cavity structure led to varying airflow distribution in the nasal cavities and the main airflow passed through the common nasal meatus. The nasal resistance in the regions of nasal valve and nasal vestibule accounted for more than a half of overall resistance. The characteristic model of nasal cavity was extracted based on the characteristic points and dimensions deducted from the original models. It showed that either the geometric structure or the air-flow field of the two kinds of model was similar. The characteristic dimensions were the characteristic parameters of nasal cavity that properly represented the original model in research for nasal cavity.

Characteristics of Nanofluids over a Non-Linearly Stretched Sheet under the Influence of Thermal Radiation and Magnetic Field

Recent studies carried out in terms of viscous flow and heat transfer of nano-fluids on the non-linear sheets. In this paper, detailed studies to understand the characteristics such as viscous flow and heat transfer of nano-fluids under the influence of thermal radiation and magnetic fields are studied using Keller-Box method. Various governing parameters affecting the viscous flow and heat transfers are drawn based on quantitative results. The raise in temperature affected the velocity to a negative value;however, the same observation was made even for the increasing magnetic field. The impact of radiation parameter is proportional seems to be proportional to temperature and it is observed to be inversely proportional with concentration.

Influence of thermal flow field of cooling tower on recirculation ratio of a direct air-cooled system for a power plant

In order to get thermal flow field of direct air-cooled system,the hot water was supplied to the model of direct air-cooled condenser(ACC). The particle image velocimetery (PIV) experiments were carried out to get thermal flow field of a ACC under different conditions in low velocity wind tunnel,at the same time,the recirculation ratio at cooling tower was measured,so the relationship between flow field characteristics and recirculation ratio of cooling tower can be discussed. From the results we can see that the flow field configuration around cooling tower has great effects on average recirculation ratio under cooling tower. The eddy formed around cooling tower is a key reason that recirculation produces. The eddy intensity relates to velocity magnitude and direction angle,and the configuration of eddy lies on the geometry size of cooling tower. So changing the flow field configuration around cooling tower reasonably can decrease recirculation ratio under cooling tower,and heat dispel effect of ACC can also be improved.

波流环境中多孔射流三维数值模拟

建立了波流环境中多孔射流的三维大涡数学模型,探讨了波流共同作用下多孔射流的扩散和稀释机制,分析了孔间距对双孔射流、射流与环境水体相互作用的影响,并给出了最优相对孔间距。模拟结果表明:在波谷相位时刻,由于横流与波浪相互作用强烈,流场内的三维涡旋结构丰富、尺度较大、数目众多,有利于射流与环境水体、射流与射流之间的掺混,这是波流环境比单一横流环境中多孔射流运动扩散效果更佳的主要原因;随着孔间距的增大,双孔射流之间的相互作用慢慢削弱,而射流与环境水体之间的相互作用却在不断增强;双孔射流在孔间距为7.0倍管口直径时扩散效果最好。

气流场驱动喷射3D打印熔融聚乳酸微细纤维及表面浸润性调控

提出了一种高速气流场驱动喷射高效三维(3D)打印熔融聚乳酸微细纤维的方法,分析了高速气流致熔融材料剪切破碎原理,研究了打印工艺中供料气压、气流流速、打印高度等关键参数对微细纤维直径分布及结构孔隙率、截面尺寸的影响规律。并对所获得的聚乳酸微细纤维进行了表面浸润性测试。结果表明,该工艺相对于静电纺丝等微细纤维制造方法,加工效率提高10倍以上。通过控制不同的打印参数,可以有效实现纤维直径在6~18μm、孔隙率在55%~96%范围内的有效调控。通过3D打印工艺,可实现具有宏观路径可控、微观具有高孔隙率微纤维结构的制作。表面浸润性结果显示,打印微细纤维由于材料分子基团及高孔隙率综合作用,具有疏水性及粘附性特征,通过对微观局部进行亲水处理,实现了同一材料局部疏水和亲水共存结构的制作,证明了该方法表面浸润性调控的有效性。

地热储层岩体粗糙裂隙的热流耦合效应研究

为了解决地热开采涉及复杂的多物理场耦合问题,提高开采效率,本文针对开采过程中的渗流-传热问题以离散元软件3DEC构建岩体粗糙裂隙热-流耦合数值模型。考虑不同三维形貌特征的岩体裂隙,模拟水力开度为19.17μm在不同流速时的水-岩温度变化规律。结果表明:由于裂隙形貌的阻滞作用,粗糙面出水口温度下降较慢,出水口温度有所上升,模型达到稳态所需的时间随流速和对流换热系数的增大而减小。裂隙形貌对流体和岩体温度分布均有影响,粗糙裂隙面的冷锋形态和裂隙面的形貌密切相关。光滑裂隙热突破快于粗糙裂隙,增加裂隙面的粗糙度有助于延长热突破时间。粗糙裂隙面相对于光滑裂隙面的总热量提取率略有提升,流速和对流换热系数的增加显著提高总热量提取率。通过本文研究可以为地热能系统的设计提供重要参数和指导,能够提高地热能开发利用效率。