具有幂律纳米流体流动的导管内辐射热传递的计算评估

利用因热源作用而收缩和膨胀的导管研究一阶化学反应和热辐射对幂律Carreau流体热质传输的影响。考虑了以热辐射形式产生热量的流体流动的体积热源和非线性热辐射。采用基于射击简单算法的RK-4方法对径向模式下的质量、动量、能量和物种浓度等基本守恒方程进行了重构和数值求解。考虑粒子的布朗性和热泳性,纳米粒子存在的模型是现象模型。将动量方程与扩展Jaffrey-Hamel问题的Carreau模型组合在一起。不同幂律指数对流体摩擦传热、传热量和传质的影响主要表现在流变性能上,说明剪切增稠型流体比剪切减薄型流体更有效。热传输率在热源处最大,在幂指数最大化时最小。这些研究可能有助于开发一种物理上合理的方法,用于系统化评估收缩/扩张通道中的流体流动和能量使用。

饲料中不同蛋白水平对雌剑尾鱼繁殖力的影响

试验旨在研究饲料中不同蛋白水平对雌剑尾鱼（一种普通的家庭观赏鱼）繁殖性能的影响。5种等能半精制饲料的蛋白水平分别为20%、30%、40%、50%和60%。繁殖性能的评价主要基于生长指标、体成分和雌亲鱼的产卵量。结果显示,20%和30%蛋白组的特定生长率最低,40%和60%蛋白组的特定生长率无显著性差异。20%蛋白组剑尾鱼的卵巢和肌肉蛋白含量最低。50%和60%蛋白组亲鱼的产卵量最高,30%和40%蛋白组次之,20%蛋白组最低。产卵量和雌剑尾鱼重量存在正相关关系,说明亲鱼规格是影响产卵量的重要因素之一。繁殖力以20%蛋白组最低,其次是30%-40%蛋白组和40%-60%蛋白组。各蛋白组间鱼苗的重量和长度以及体成分均无显著差异。雌剑尾鱼繁殖期间饲料蛋白需求取决于亲鱼个体生长和繁殖过程中鱼苗的适宜产量。基于以上结果,建议雌剑尾鱼繁殖期间饲料蛋白含量要高于30%。

Effects of Thermal Radiation and Slip Mechanism on Mixed Convection Flow of Williamson Nanofluid Over an Inclined Stretching Cylinder

The current investigation highlights the mixed convection slip flow and radiative heat transport of uniformly electrically conducting Williamson nanofluid yield by an inclined circular cylinder in the presence of Brownian motion and thermophoresis parameter.A Lorentzian magnetic body force model is employed and magnetic induction effects are neglected.The governing equations are reduced to a system of nonlinear ordinary differential equations with associated boundary conditions by applying scaling group transformations.The reduced nonlinear ordinary differential equations are then solved numerically by Runge-Kutta-Fehlberg fifth-order method with shooting technique.The effects of magnetic field,Prandtl number,mixed convection parameter,buoyancy ratio parameter,Brownian motion parameter,thermophoresis parameter,heat generation/absorption parameter,mass transfer parameter,radiation parameter and Schmidt number on the skin friction coefficient and local Nusselt are analyzed and discussed.It is found that the velocity of the fluid decreases with decrease in curvature parameter,whereas it increases with mixed convection parameter.Further,the local Nusselt number decreases with an increase in the radiation parameter.The numerical comparison is also presented with the existing published results and found that the present results are in excellent agreement which also confirms the validity of the present methodology.

Dissipative flow features of Carreau nanofluid with thermal radiation inside plane wall channel:Jeffery-Hamel analysis

The current article communicates a numerical investigation on laminar flow of dissipative generalized Newtonian Carreau nanofluid flowing through vertical conduit with converging and diverging plane walls.Thermal and concentration characteristics due to enthalpy change,activation energy,and non-linear thermal radiation have been examined in the presence of buoyancy forces.The channel walls for both temperature and volumetric fraction are assumed to be isothermal.The instability mechanism of nanofluids is reported using a two-phase nanofluid model,which works reasonably well for nanoparticle concentrations below a certain threshold.A Jeffery-Hamel(J-H)flow model is developed by assuming an incompressible purely radial flow of Carreau nanofluids with heat and mass transportation.Using the suitable non-dimensional variables,the resulting nonlinear partial differential equations are turned into a system of ordinary differential equations.The modified governing equations are then numerically solved using the built-in boundary value problem solver bvp4c,on the template form of commercial software MATLAB.The impacts of material,geometrical and thermophysical parameters governing the J-H problem are discussed and illustrated.Results indicate that higher buoyance forces incline the velocity profiles in converging enclosure,while a slight reduction is perceived in opposing forces.A significant decrease of wall heat transmission is reflected for larger values of activation energy and radiation parameter.For endorsing this communication,a comparison analysis is established with existing research and noticed a remarkable agreement.Practically,the flow inside converging and diverging channels are deployed in nuclear reactors that use plate-type nuclear energies,high heat-flux condensed heat exchangers,high-performance micro-electronic cooling systems,jets,rockets nozzles,and jet propulsion inlet.

Thermally stratified flow of hybrid nanofluids with radiative heat transport and slip mechanism: multiple solutions

Research on flow and heat transfer of hybrid nanofluids has gained great significance due to their efficient heat transfer capabilities.In fact,hybrid nanofluids are a novel type of fluid designed to enhance heat transfer rate and have a wide range of engineering and industrial applications.Motivated by this evolution,a theoretical analysis is performed to explore the flow and heat transport characteristics of Cu/Al_(2)O_(3) hybrid nanofluids driven by a stretching/shrinking geometry.Further,this work focuses on the physical impacts of thermal stratification as well as thermal radiation during hybrid nanofluid flow in the presence of a velocity slip mechanism.The mathematical modelling incorporates the basic conservation laws and Boussinesq approximations.This formulation gives a system of governing partial differential equations which are later reduced into ordinary differential equations via dimensionless variables.An efficient numerical solver,known as bvp4c in MATLAB,is utilized to acquire multiple(upper and lower)numerical solutions in the case of shrinking flow.The computed results are presented in the form of flow and temperature fields.The most significant findings acquired from the current study suggest that multiple solutions exist only in the case of a shrinking surface until a critical/turning point.Moreover,solutions are unavailable beyond this turning point,indicating flow separation.It is found that the fluid temperature has been impressively enhanced by a higher nanoparticle volume fraction for both solutions.On the other hand,the outcomes disclose that the wall shear stress is reduced with higher magnetic field in the case of the second solution.The simulation outcomes are in excellent agreement with earlier research,with a relative error of less than 1%.