Viscous dissipation

  • 文章类型: Journal Article
    进行了有限差分数值模拟审查,以评估产热的综合影响,浮力,通过考虑斜坡表面浓度和温度,沿着指数加速的可渗透垂直板流动的非稳态水磁混合对流化学反应和辐射卡森流体中的粘性耗散和焦耳加热在多孔介质中。通过采用胜任的隐式Crank-Nicolson有限差分程序,对描述流动模型的无量纲非线性耦合PDE进行了数值处理。速度的方差,温度,由于流动约束参数的不同,浓度分布通过图形表示暴露出来。皮肤摩擦的计算结果,努塞尔和舍伍德数字以表格形式描绘。研究的最终结果揭示了热辐射的影响,粘性耗散,和产热参数扩大了温度和速度分布。流体运动随着Casson参数和磁场强度的增长而收缩。上升的化学反应参数抑制了浓度和速度分布。非常重要的是,流体动量是有区别的,温度,在等温板温度的情况下,浓度比斜坡壁温度更快。这种研究可能会发现特定的工业和医疗用途,例如玻璃制造,原油净化,润滑,造纸,心血管设计中的血液运输研究,等。
    A finite difference numerical simulation scrutiny is executed to evaluate the combined impacts of heat generation, buoyancy forces, viscous dissipation and Joule heating in unsteady hydro-magnetic mixed convective chemically reactive and radiative Casson fluid flowing along an exponentially accelerating permeable vertical plate engrossed in a porous media by considering ramp surface concentration and temperature. The dimensionless non-linear coupled PDEs describing the flow model are dealt numerically by adopting the competent implicit Crank-Nicolson finite difference procedure. The variance of velocity, temperature, and concentration distributions are exposed via graphical representations due to the dissimilarity of the flow restrained parameters. Computational outcomes of the skin-friction, Nusselt and the Sherwood numbers are portrayed in the tabular pattern. The final outcomes of the research exposed that the impacts of thermal radiation, viscous dissipation, and heat production parameters enlarges the temperature and velocity distributions. The fluid motion deflates for growing Casson parameter and magnetic field intensity. The rising chemical reaction parameter suppresses the concentration and velocity distributions. Very importantly it is distinguished that fluid momentum, temperature, and concentration are quicker in the instance of isothermal plate temperature than ramp wall temperature. This kind of research may find specific industrial and medical utilizations such as glass manufacturing, crude oil purification, lubrication, paper production, blood transport study in cardiovascular design, etc.
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  • 文章类型: Journal Article
    作为一种新型的流体功能材料,磁流体动力学(MHD)微极性流体具有光的特殊性质,热,磁性等等。具有很强的现实意义。流动的特点,基于当前数值工作中的微极性流体理论,研究了经过拉伸板的MHD微极性纳米流体边界层中的传热和传质。在磁场存在的情况下,考虑了Dufour效应和Soret效应引起的粘性耗散和交叉扩散。采用一阶滑移速度条件。数学模型是基于假设建立的。采用矩阵乘法的配置谱方法(CSM)求解二维无量纲非线性部分控制方程。开发了基于CSM的程序代码,验证和使用。微旋转的耦合效应,Dufour效应,Soret效应,磁场以及流的一阶滑移速度边界条件,传热和传质被揭示。此外,详细分析了当地努塞尔数和舍伍德数的变化趋势。数值结果表明,考虑滑移条件和磁场,可以明显抑制流体流动。随着滑移参数δ和磁参数M的上升,边界层中的速度逐渐降低;进一步,温度和浓度都会增加。另一方面,在材料参数K的影响下,可以注意到相反的趋势。Ec和Df增加了温度;而,Sr导致浓度激增。在Dufour效应下,温度升高约79.73%,在Soret效应下,Sh增大约38.15%。当K=5.0时,浓度边界层降低约37.50%。
    As a novel fluid of functional material, magnetohydrodynamic (MHD) micropolar fluid has the special properties of light, heat, magnetic and so on. It is of highly practical significance. The characteristics of flow, heat and mass transfer in MHD micropolar nanofluid boundary layer past a stretching plate are investigated based on the micropolar fluid theory in the present numerical work. In the presence of magnetic field, viscous dissipation and the cross-diffusion caused by Dufour effect and Soret effect are considered. First order slip velocity condition is employed. Mathematical models are built based on the assumptions. Collocation spectral method (CSM) via matrix multiplication is adopted to solve the two-dimensional dimensionless nonlinear partial governing equations. The program codes based on CSM is developed, validated and employed. The coupled effects of microrotation, Dufour effect, Soret effect, magnetic field as well as first order slip velocity boundary condition on the flow, heat and mass transfer are revealed. Besides, the variation trends of local Nusselt number and Sherwood number are analyzed in detail. The numerical results indicate that the fluid flow can be suppressed obviously in the consideration n of slip condition and magnetic field. As slip parameter δ and magnetic parameter M rise, the velocity in the boundary layer becomes lower gradually; further, both temperature and concentration increase. On the other hand, the opposite trend can be noticed with the effect of material parameter K. Moreover, Ec and Df augment the temperature; while, Sr leads to an upsurge in concentration. The temperature rises by about 79.73% with Dufour effect and Sh enlarges by a factor of about 38.15% with Soret effect. The concentration boundary layer decreases by about 37.50% is when K=5.0.
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  • 文章类型: Journal Article
    在具有传热的非牛顿流体的各种流动机制中,熵优化的审查得到了令人难以置信的增强。通过研究非牛顿威莱姆森流体稳定流动中的不可逆性源,在当前的工作中进行了熵产生的分析。当前的研究具有通过考虑对流辐射边界条件来研究具有流动现象的传热机理的重要方面。假设水平MHD通道具有两个平行板,以通过考虑流体的可变粘度来建立流动现象的数学模型。热辐射的物理影响的贡献,焦耳加热,并将粘性耗散插值到本构能量方程中。当前分析的完整流程以常微分方程的形式建立,该常微分方程通过相似性变量的贡献进一步采用无量纲系统的形式。提出了与相关参数相关的流动现象的物理特征的图形检查。这项研究表明,较高的辐射参数和Brinkman数决定了系统的熵。此外,温度分布经历了一个增加的机制,并在下板处改善了传导辐射参数。
    The scrutinization of entropy optimization in the various flow mechanisms of non-Newtonian fluids with heat transfer has been incredibly enhanced. Through the investigation of irreversibility sources in the steady flow of a non-Newtonian Willaimson fluid, an analysis of entropy generation is carried out in this current work. The current study has an essential aspect of investigating the heat transfer mechanism with flow phenomenon by considering convective-radiative boundary conditions. A horizontal MHD channel is assumed with two parallel plates to develop a mathematical model for the flow phenomenon by considering the variable viscosity of the fluid. The contribution of physical impacts of thermal radiation, Joule heating, and viscous dissipation is interpolated in the constitutive energy equation. The complete flow of the current analysis is established in the form of ordinary differential equations which further take the form of the dimensionless system through the contribution of the similarity variables. A graphical scrutinization of the physical features of the flow phenomenon in relation to the pertinent parameters is proposed. This study reveals that the higher magnitude of radiation parameter and Brinkman number dominates the system\'s entropy. Moreover, the temperature distribution experiences an increasing mechanism with improved conduction-radiation parameter at the lower plate.
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  • 文章类型: Journal Article
    本文首次提出了任意形状三角形管道内流体流动和传热的解析解。以前的解析解仅限于等腰三角形管道的特殊情况。文献没有关于任意形状的三角形管道的一般情况的解析解的报道。由于流体流过非圆形通道在工业中的重要作用以及大量的三角形,需要一种解决所有三角形传热问题的方法。在这项工作中,首次解决了在壁的热通量恒定的情况下,流体流过具有任意三角形横截面的通道的传热问题,考虑粘性耗散。这里,推导了流动和传热方程的泛函,并使用Ritz方法求解所得的Euler-Lagrange方程。详细研究了管道几何形状对速度分布和摩擦系数的影响。在冷却和加热情况下,都研究了Brinkman数对温度分布和Nusselt数的影响。结果表明,临界Brinkman数可以区分冷却和加热情况,并代表Nusselt数接近无穷大的临界点。在壁冷却和加热模式下,努塞尔数的值都随着布林克曼数的增加而减小。还发现等边三角形表现出最小的摩擦系数和Poiseuille数的最大值。
    This paper presents an analytical solution for fluid flow and heat transfer inside arbitrarily-shaped triangular ducts for the first time. The former analytical solutions are limited to the special case of isosceles triangular ducts. The literature has no report about the analytical solution for the general case of arbitrarily-shaped triangular ducts. Due to the significant role of fluid flow through non-circular channels in industry and the large number of triangular shapes, a method for solving the heat transfer problem for all triangular shapes is needed. The heat transfer of a fluid flow through a channel with an arbitrary triangular cross-section for the case of constant heat flux at the walls is solved in this work for the first time, considering viscous dissipation. Here, the functionals of flow and heat transfer equations are derived, and the resulting Euler-Lagrange equations are solved using the Ritz method. The effect of the duct geometry on the velocity profile and friction coefficient is studied in detail. The effect of the Brinkman number on the temperature distribution and Nusselt number is investigated for both cooling and heating cases. The results reveal that the critical Brinkman Number distinguishes between the cooling and heating cases and represents the critical point at which the Nusselt number approaches infinity. The value of the Nusselt number decreases with the increase of the Brinkman number in both the wall cooling and heating modes. It is also found that the equilateral triangle exhibits the minimum friction coefficient and the maximum value of the Poiseuille number.
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  • 文章类型: Journal Article
    非牛顿流体在涉及传热和传质的情况下是必不可少的。当将纳米颗粒(0.01≤φ≤0.03)添加到这些流体中时,传热和传质过程会提高效率。本研究采用了一种计算方法来研究非牛顿纳米流体在直立圆锥表面上的行为。还考虑了粘性耗散(0.3≤Ec≤0.9)和磁流体动力学(MHD)(1≤M≤3)。此外,我们探索微生物如何影响流体的质量和传热。使用相似性变换将物理模型的控制方程转换为常微分方程(ODE),以使分析更容易。使用MATLAB中的Bvp4c求解器对ODE进行数值求解。势头,热,浓度,在当前的研究中,微生物扩散曲线以图形方式表示。MHD(1≤M≤3)效应改善了微生物的扩散,导致传热和传质率增加18%和19%,分别,根据我们的结果。此外,我们的研究结果与现有文献的比较表明有希望的一致性.
    Non-Newtonian fluids are essential in situations where heat and mass transfer are involved. Heat and mass transfer processes increase efficiency when nanoparticles (0.01≤φ≤0.03) are added to these fluids. The present study implements a computational approach to investigate the behavior of non-Newtonian nanofluids on the surface of an upright cone. Viscous dissipation (0.3≤Ec≤0.9) and magnetohydrodynamics (MHD) (1≤M≤3) are also taken into account. Furthermore, we explore how microorganisms impact the fluid\'s mass and heat transfer. The physical model\'s governing equations are transformed into ordinary differential equations (ODEs) using a similarity transformation to make the analysis easier. The ODEs are solved numerically using the Bvp4c solver in MATLAB. The momentum, thermal, concentration, and microbe diffusion profiles are graphically represented in the current research. MHD (1≤M≤3) effects improve the diffusion of microbes, resulting in increased heat and mass transfer rates of 18 % and 19 %, respectively, based on our results. Furthermore, a comparison of our findings with existing literature demonstrates promising agreement.
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  • 文章类型: Journal Article
    在这次调查中,研究了由于具有粘性耗散和热辐射的倾斜表面而引起的微极性二元流体对不稳定的磁性多孔对流传输的粘性耗散结果。粘性耗散在工业应用中起着值得注意的作用。使用相似性分析,将控制PDE转换为具有Boussinesq近似的组合ODE。使用带有“ODE45MATLAB”编码辅助的拍摄方法解析获得的非线性ODE。数值结果以图形方式显示了各种无量纲参数和数字,包括温度,浓度,速度,和微旋转。温度,微旋转,速度场随着埃克特数的增加而升级。辐射参数和可变粘度参数增加流体的流速。增加辐射参数,吸力参数,和Prandtl数字降低流体温度。在冷却和加热模式下,浮力参数对流体颗粒的速度和微旋转具有对称影响。改进Eckert编号,倾斜角度,施密特数,普朗特号,和磁参数减少皮肤摩擦。由于较大的Prandtl数值,热传递速率在数量上增加。上升的普朗特,埃克特,施密特数字加速了传质速率。当前的研究结果与以前发表的文章的结果进行了比较,具有很好的一致性。
    In this investigation , the consequence of viscous dissipation on the unstable magneto porous convective transport by a micropolar binary fluid due to an inclined surface with viscous dissipation and thermal radiation is examined. Viscous dissipation plays a noteworthy role in industrial applications. The governing PDEs are converted to combined ODEs with the Boussinesq approximation using a similarity analysis. The obtained non-linear ODEs are resolved using the shooting method with \"ODE45 MATLAB\" coding assistance. The numerical outcomes are revealed graphically for various dimensionless parameters and numbers, including temperature, concentration, velocity, and micro-rotation. The temperature, micro-rotation, and velocity fields escalate with increasing Eckert numbers. The radiation parameter and variable viscosity parameter increase the flow rate of the fluid. Increasing radiation parameters, suction parameters, and Prandtl numbers lessen the fluid temperature. The buoyancy parameters have symmetrical impacts on the velocity and microrotation of fluid particles in the cooling and heating modes. Improving Eckert number, inclined angle, Schmidt number, Prandtl number, and magnetic parameter reduces skin friction. The heat transmission rate escalates in quantity due to larger Prandtl number values. Rising Prandtl, Eckert, and Schmidt numbers accelerate the mass transfer rate. The current research result is compared to previously published article\'s result with good agreement.
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  • 文章类型: Journal Article
    转化生长因子(TGF)-β1是一种多功能细胞因子,在健康和疾病中起重要作用。以前的研究表明,TGFβ1激活,信令,和下游细胞反应,包括上皮-间质转化(EMT)和细胞凋亡受细胞外基质的弹性或刚度调节。然而,体内的组织不是纯弹性的,相反,它们是粘弹性的。基质粘弹性如何影响TGFβ1下游的细胞命运决定仍然未知。这里,我们合成了模拟乳腺肿瘤组织粘弹性的聚丙烯酰胺水凝胶。我们发现,增加基质粘性耗散减少TGFβ1诱导的细胞扩散,F-肌动蛋白应力纤维形成,和EMT相关的基因表达变化,并促进TGFβ1诱导的乳腺上皮细胞凋亡。此外,与在几乎弹性的基质上培养的细胞相比,在粘弹性基质上培养的乳腺上皮细胞中,TGFβ1诱导的整合素连接激酶(ILK)的表达和ILK与黏带素在细胞粘附处的共定位减弱。ILK的过表达促进TGFβ1诱导的EMT并减少在粘弹性基质上培养的细胞中的凋亡,提示ILK在调节TGFβ1下游响应基质粘弹性的细胞命运中起重要作用。
    Transforming growth factor (TGF)-β1 is a multifunctional cytokine that plays important roles in health and disease. Previous studies have revealed that TGFβ1 activation, signaling, and downstream cell responses including epithelial-mesenchymal transition (EMT) and apoptosis are regulated by the elasticity or stiffness of the extracellular matrix. However, tissues within the body are not purely elastic, rather they are viscoelastic. How matrix viscoelasticity impacts cell fate decisions downstream of TGFβ1 remains unknown. Here, we synthesized polyacrylamide hydrogels that mimic the viscoelastic properties of breast tumor tissue. We found that increasing matrix viscous dissipation reduces TGFβ1-induced cell spreading, F-actin stress fiber formation, and EMT-associated gene expression changes, and promotes TGFβ1-induced apoptosis in mammary epithelial cells. Furthermore, TGFβ1-induced expression of integrin linked kinase (ILK) and colocalization of ILK with vinculin at cell adhesions is attenuated in mammary epithelial cells cultured on viscoelastic substrata in comparison to cells cultured on nearly elastic substrata. Overexpression of ILK promotes TGFβ1-induced EMT and reduces apoptosis in cells cultured on viscoelastic substrata, suggesting that ILK plays an important role in regulating cell fate downstream of TGFβ1 in response to matrix viscoelasticity.
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    求助全文

  • 文章类型: Journal Article
    这项工作的目的是研究一个完全开发的动态和热行为,层状,具有菱形横截面的微通道中的气流。由于新的制造技术,具有菱形横截面的微管最近受到了更多的关注。通过使用商业CDF代码并假设滑移和H2边界条件来求解动量和能量平衡方程。还考虑了壁和相邻流体之间的温度跳跃。通过使用文献中可用的数据,根据滑移流态中的速度分布和连续流态中的努塞尔数,检查了数值结果的准确性。还要研究几何对流体行为的影响,考虑了菱形侧角的几个值。数值结果表明,稀疏度和几何特性显着影响努塞尔数。
    This work aimed to numerically investigate the dynamic and thermal behavior of a fully developed, laminar, gaseous flow in a microchannel featuring a rhombic cross-section. Due to new fabrication techniques, microducts with rhombic cross-sections have recently received more attention. The momentum and energy balance equations were solved by using a commercial CDF code and assuming the slip and the H2 boundary conditions. The temperature jump between the wall and the adjacent fluid was also taken into account. The accuracy of the numerical results was checked by using the data available in the literature in terms of velocity profiles in the slip flow regime and the Nusselt number in the continuum flow regime. To also investigate the geometry effects on the fluid behavior, several values of the side angle of the rhombus were considered. The numerical results revealed that the rarefaction degree and geometrical properties significantly affected the Nusselt number.
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  • 文章类型: Journal Article
    本研究致力于分析具有双重可用性的拉伸/收缩片材上的纳米流体流动的封闭形式溶液。流动是通过二维边界层理论发展的。使用适当的张量来生成连续性,能源,和动量方程。通过采用有利的相似性变量,将控制偏微分方程(PDE)转换为无量纲非线性常微分方程(ODE)。在某些条件下,能量和动量的无量纲ODE以封闭形式产生了双重性质的解。为了处理纳米流体,使用Koo-Kleinstreuer和Li(KKL)模型,并使用著名的软件Maple求解方程。孔隙度Φ的影响,抽吸/注射fw,拉伸/收缩λ,和磁效应M对皮肤摩擦的影响,速度,温度,流线得到了很好的探索和展示。稳定解的结果表明,上分支的流体速度随着磁参数M的升高而增加,而下分支的流体速度随着M的升高而降低。此外,CuO纳米流体的速度受纳米粒子的体积分数的影响,随着体积分数的增加导致速度降低。在下部和上部分支上,随着Biot数的增加,温度曲线会有所改善。另一方面,随着磁参数的变化和磁场的增加,局部Nusselt数相对于吸入/注入减少,以及上部分支的传热速率降低。
    Present study is dedicated to analyze the closed form solution of nanofluid flow over a stretching/shrinking sheet with dual availability. Flow is developed through two-dimensional boundary layer theory. Appropriate tensor is used to generate the continuity, energy, and momentum equations. Converted governing partial differential equations (PDEs) into dimensionless non-linear ordinary differential equations (ODEs) by adoption of favorable similarity variables. The dimensionless ODEs of energy and momentum produced a dual nature solution in closed form under certain conditions. To deal with the nanofluid, the Koo-Kleinstreuer and Li (KKL) model is used, and the equations are solved using well-known software Maple. The effect of porosity Φ, suction/injection fw, stretching/shrinking λ, and magnetic effect M on skin friction, velocity, temperature, and streamlines are well explored and showcased. The results for the stable solutions have been showed that the upper branch\'s fluid velocity is increasing as the magnetic parameter M rises whereas the lower branch\'s fluid velocity is decreasing as M rises. Additionally, the CuO-nanofluid\'s velocity is impacted by the volume fraction of nanoparticles, with an increase in volume fraction causing a decrease in velocity. On both the lower and upper branches, the temperature profile is seen to improve as the Biot number increases. On the other hand, as the magnetic parameter varies and the magnetic field increases, the local Nusselt number against suction/injection decreases, as well as the rate of heat transfer in the upper branch decreases.
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  • 文章类型: Journal Article
    这项研究仅限于可变密度和磁流体动力学对多孔空间中WilliamsonSakiadis流的影响的数值评估。在这项研究中,焦耳加热,耗散,在光学致密的灰色流体上遇到产热效应。作为流动几何形状的倾斜移动表面被认为引起流体流动。提出的现象以偏微分方程形式给出了数学结构。然后使用无量纲变量使这些偏微分方程无量纲。然后通过流函数公式将获得的偏微分方程中的无量纲模型更改为常微分方程。已使用bvp4c求解器求解了一组变换方程。速度场的数值落差,温度场,皮肤摩擦,和传热率在图表和表格中说明了流量参数变化。得出的结论是,密度变化参数的固定值证实了速度场的降低和流体温度的升高。当威廉姆森流体参数增强时,流体速度和温度都相应地上升。磁数的大小越来越大,辐射参数,产生热量,和Eckert数升高流体的温度。多孔介质参数的升高会削弱流体速度。随着辐射参数和密度变化参数的增加,皮肤摩擦减少。将本解决方案与已经发布的解决方案进行比较,以验证当前模型。比较得出的结论是,这两个结果非常吻合,认可当前答案的真实性。
    This study is confined to the numerical evaluation of variable density and magnetohydrodynamics influence on Williamson Sakiadis flow in a porous space. In this study, Joule heating, dissipation, heat generation effect on optically dense gray fluid is encountered. The inclined moving surface as flow geometry is considered to induce the fluid flow. A proposed phenomenon is given a mathematical structure in partial differential equations form. These partial differential equations are then made dimensionless using dimensionless variables. The obtained dimensionless model in partial differential equations is then changed to ordinary differential equations via stream function formulation. A set of transformed equations has been solved with bvp4c solver. The numerical fallout of velocity field, temperature field, skin friction, and heat transfer rate are illustrated in graphs and tables with flow parametric variations. Conclusion is drawn that mounting values of density variation parameter confirm the reduction in velocity field and augmentation in temperature of the fluid. When Williamson fluid parameter enhances, both fluid velocity and temperature are rising correspondingly. Growing magnitudes of the magnetic number, radiation parameter, heat generation, and Eckert number rise the temperature of the fluid. A rise in a porous medium parameter weakens the fluid velocity. Skin friction is reducing as radiation parameter and density variation parameter are increased. The present solutions are compared to those that have already been published in order to validate the current model. The comparison leads to the conclusion that the two outcomes are in excellent agreement, endorsing the veracity of the current answers.
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