Nonlinear Thermal Effects Research Articles

Numerical simulation for bioconvectional flow of burger nanofluid with effects of activation energy and exponential heat source/sink over an inclined wall under the swimming microorganisms

Nanofluids has broad applications such as emulsions, nuclear fuel slurries, molten plastics, extrusion of polymeric fluids, food stuffs, personal care products, shampoos, pharmaceutical industries, soaps, condensed milk, molten plastics. A nanofluid is a combination of a normal liquid component and tiny-solid particles, in which the nanomaterials are immersed in the liquid. The dispersion of solid particles into yet another host fluid will extremely increase the heat capacity of the nanoliquid, and an increase of heat efficiency can play a significant role in boosting the rate of heat transfer of the host liquid. The current article discloses the impact of Arrhenius activation energy in the bioconvective flow of Burger nanofluid by an inclined wall. The heat transfer mechanism of Burger nanofluid is analyzed through the nonlinear thermal radiation effect. The Brownian dispersion and thermophoresis diffusions effects are also scrutinized. A system of partial differential equations are converted into ordinary differential equation ODEs by using similarity transformation. The multi order ordinary differential equations are reduced to first order differential equations by applying well known shooting algorithm then numerical results of ordinary equations are computed with the help of bvp4c built-in function Matlab. Trends with significant parameters via the flow of fluid, thermal, and solutal fields of species and the area of microorganisms are controlled. The numerical results for the current analysis are seen in the tables. The temperature distribution increases by rising the temperature ratio parameter while diminishes for a higher magnitude of Prandtl number. Furthermore temperature-dependent heat source parameter increases the temperature of fluid. Concentration of nanoparticles is an decreasing function of Lewis number. The microorganisms profile decay by an augmentation in the approximation of both parameter Peclet number and bioconvection Lewis number.

Influence of Variable Properties on Quadratic Convective Flow of Casson Nanofluid Past an Inclined Plane

In this study, the combined effects of thermophysical fluid properties alongside nonlinear thermal and solutal convective processes in an inclined flow region containing Casson nanofluid subjected to slip and convective boundary conditions are considered. Application of induced non-uniform magnetic field strength applied perpendicular to the flow plane and the buoyancy influences are believed responsible for the quadratic convection rate. The prime PDEs are renewed to systems of ODEs via applicable transformations and similarity variables. Assuming a series trial solution, the flow distribution results were obtained numerically by collocation approach with Legendary polynomial basis function. Validation of the numerical results plays favorably when compared with the weighted residual method (Galerkin) and the existing literature. The results reveal that; Casson fluid exhibit a solid characteristic when yield stress is more than the shear stress, pronouncement of nonlinear solutal and thermal buoyancy effects predicts the acceleration of the flow fields greatly compared to the linear model, adherence between the fluid particles and flow surface displayed retardation in shear force thus enhanced the motion of Casson fluid and diminished the energy fields, surface suspension suppressesbthe flow but energizes both temperature and nanoparticle volume fraction profiles.

MHD and nonlinear thermal radiation effects on hybrid nanofluid past a wedge with heat source and entropy generation

PurposeThis study aims to investigate the irreversibility associated with the Fe3O4–Co/kerosene hybrid-nanofluid past a wedge with nonlinear radiation and heat source.Design/methodology/approachThis study reports the numerical analysis of the hybrid nanofluid model under the implications of the heat source and magnetic field over a static and moving wedge with slips. The second law of thermodynamics is applied with nonlinear thermal radiation. The system that comprises differential equations of partial derivatives is remodeled into the system of differential equations via similarity transformations and then solved through the Runge–Kutta–Fehlberg with shooting technique. The physical parameters, which emerges from the derived system, are discussed in graphical formats. Excellent proficiency in the numerical process is analyzed by comparing the results with available literature in limiting scenarios.FindingsThe significant outcomes of the current investigation are that the velocity field uplifts for higher velocity slip and magnetic strength. Further, the heat transfer rate is reduced with the incremental values of the Eckert number, while it uplifts with thermal slip and radiation parameters. An increase in Brinkmann’s number uplifts the entropy generation rate, while that peters out the Bejan number. The results of this study are of importance involving in the assessment of the effect of some important design parameters on heat transfer and, consequently, on the optimization of industrial processes.Originality/valueThis study is original work that reports the hybrid nanofluid model of Fe3O4–Co/kerosene.

Real-time core temperature prediction of prismatic automotive lithium-ion battery cells based on artificial neural networks

For modeling of the non-linear heat generation and thermal effects in Li-ion batteries, artificial neural networks are a great solution to represent the thermal behavior for the battery management system in an electric vehicle. Several studies have proven the high accuracy with large benefits in computing-time and complexity compared to detailed electrochemical–thermal models. Commonly used feedforward networks need to prove suitability for dynamic applications but are always limited due to missing information about the previous time steps or need external sensor information. In this work, a novel Nonlinear AutoRegressive with eXogenous (NARX)-network is developed and parameterized for a large 25Ah prismatic cell. The NARX is compared to a feedforward using the same general structure and input data in terms of training, validation behavior, long-term prediction and dynamic driving application. Both ANN approaches prove to be adequate for the temperature prediction with an accuracy within 1K during long-term prediction of 10h. Additionally, in a BEV application with real-time requirements the thermal models predicting the dynamic temperature behavior with high precision and robustness without even a temperature input in case of the NARX-approach.

Design of intelligent computing networks for numerical treatment of thin film flow of Maxwell nanofluid over a stretched and rotating surface

In this study, a novel application of backpropagated Levenberg-Marquardt neural networks (LM-NN) based computational intelligent heuristics is presented to interpret the analysis of Maxwell nanofluid thin film flow over a stretchable and rotating disk by considering magnetic and non-linear thermal radiation effects. Utilizing the Buongiorno model, thermophoretic and Brownian motion features of nanofluid are captured. The mathematical model in terms of partial differential equations (PDEs) is reduced to ordinary differential equations (ODEs) by incorporating the similarity transformations. The Adams numerical technique is utilized for generation of a dataset for proposed LM-NN in case of sundry scenarios of TFFPMN by variation of Deborah number, thermophoresis number, Schmidt number, radiation and Brownian motion variables. The training, testing and validation of the intelligent solver LM-NN is performed to find the solution of TFFPMN for various scenarios. Comparison with standard solution verified the precision of LM-NN scheme for the solution of TFFPMN model through mean square error based figure of merit, regression analysis, absolute error analysis and histograms. It is found that radial and azimuthal velocities are decaying functions of Deborah number. Further the nanofluid temperature enhances against higher radiation and thermophoresis parameters. The comparative assessment is performed to validate the present results.

Analysis of Electrothermal Effects in Devices and Arrays in InGaP/GaAs HBT Technology

In this paper, the dc electrothermal behavior of InGaP/GaAs HBT test devices and arrays for power amplifier output stages is extensively analyzed through an efficient simulation approach. The approach relies on a full circuit representation of the domains, which accounts for electrothermal effects through the thermal equivalent of the Ohm’s law and can be solved in any commercial circuit simulator. In particular, the power-temperature feedback is described through an equivalent thermal network automatically obtained by (i) generating a realistic 3-D geometry/mesh of the domain in the environment of a numerical tool with the aid of an in-house routine; (ii) feeding the geometry/mesh to FANTASTIC, which extracts the network without performing simulations. Nonlinear thermal effects adversely affecting the behavior of devices/arrays at high temperatures are included through a calibrated Kirchhoff’s transformation. For the test devices, the thermally-induced distortion in I–V curves is explained, and the limits of the safe operating regions are identified for a wide range of bias conditions. A deep insight into the electrothermal behavior of the arrays is then provided, with particular emphasis on the detrimental nonuniform operation. Useful guidelines are offered to designers in terms of layout and choice of the ballasting strategy.

Dynamics of Activation Energy and Nonlinear Mixed Convection in Darcy-Forchheimer Radiated Flow of Carreau Nanofluid Near Stagnation Point Region

Abstract In this research work, heat and mass transport and radiated, two-dimensional, steady, incompressible nanofluid flow of non-Newtonian material (Carreau fluid) over a stretchable moving surface of sheet is examined. The flow is saturated through Darcy-Forchheimer porous medium and generated by stretching phenomenon. Furthermore, magnetodydrodynamics (MHD), mixed convection, heat generation/absorption, nonlinear thermal radiation, thermophoresis diffusion, activation energy, Brownian motion, and chemical reaction effects are accounted to develop the governing expressions, i.e., momentum, energy, and concentration for the considered flow problem. The governing equations are first altered into nonlinear ordinary differential equations with the help of appropriate similarity variables and then computational results are computed by Built-in-Shooting technique via mathematica. The salient aspects of sundry variables are discussed graphically on the velocity field, skin friction coefficient, temperature profile, Nusselt number, concentration field, and Sherwood number. Outcomes illustrate that the velocity field and temperature profile have contrast behavior against higher values of magnetic parameter. Also, the engineering quantities are discussed numerically with the help of important flow variables and the results are demonstrated through tables.

Data-driven LPV model predictive control of a cold atmospheric plasma jet for biomaterials processing

Cold atmospheric plasmas (CAPs) are increasingly used for treatment of complex surfaces in biomedical and biomaterials processing applications. However, the multivariable, distributed-parameter, and nonlinear nature of CAP dynamics and plasma–surface interactions, coupled with the sensitivity of plasmas to exogenous disturbances, make their safe, reproducible and effective operation challenging. This paper adopts a data-driven linear parameter-varying (LPV) modeling framework to learn a control-oriented model for predictive control of a kHz-excited atmospheric pressure plasma jet in Helium. A hierarchical model-based control strategy is proposed based on a supervisory LPV-based model predictive controller (LPV–MPC) to regulate the nonlinear thermal effects of plasma on a surface. Real-time control experiments demonstrate the effectiveness of the proposed LPV–MPC strategy for the multivariable control of surface temperature and plasma optical intensity, as well as for controlling the spatial delivery of the cumulative thermal effects of the plasma jet on a surface.

Nonlinear thermal radiation and temperature dependent viscosity effects on MHD heat and mass transfer in a thin liquid film over a stretching surface

Nonlinear thermal radiation and temperature dependent viscosity effects on MHD heat and mass transfer in a thin liquid film over a stretching surface

Effects of nonlinear thermal radiation over magnetized stagnation point flow of Williamson fluid in porous media driven by stretching sheet

AbstractIn this study, the stagnation point flow of a magnetized Williamson fluid past a stretching sheet in the presence of nonlinear thermal radiation and buoyancy effect is studied. The present situation is remodeled using similarity transformation that transforms the flow model of partial differential equations into the set of nonlinear ordinary differential equations. The fourth‐order Runge‐Kutta scheme and shooting method are employed to solve these reduced equations. The effects of various associated parameters over the velocity and temperature profiles are plotted and the outcome of each associated parameter is discussed through graphs. The key findings are noted as follows: the velocity profile declines with an increase in the magnetic force number, and an increment in buoyancy parameter leads to the increase in the boundary layer thickness and decrease in the thickness of the thermal boundary layer.

Impact of Hall effect, nonlinear radiation and heat source on MHD Couette–Poiseuille flow of nanoliquid through a rotating channel

PurposeThis report offers the detailed investigation of Couette–Poiseuille flow of nanoliquid with varying viscosity. The analysis is carried out by considering flow between two parallel plates in a rotating permeable channel with the aid of nonlinear thermal radiation and Hall effect. The predominant equations governing the physical phenomenon are demonstrated using the Buongiorno model.Design/methodology/approachNumerical computation for the demonstrated physical problem is achieved through the implementation of the Runge–Kutta–Fehlberg fourth–fifth-order method along with shooting technique.FindingsThe theoretical view of Brownian motion, nonlinear radiation, Hall effect and thermophoresis parameter is presented graphically.Originality/valueIt is revealed that flow velocity increases with the upper wall motion parameter and magnetic field. Also, it is established that an increase in the Nusselt number is achieved for increasing values of nonlinear radiation parameter.

A DOMIAN DECOMPOSITION METHOD FOR STEADY FREE CONVECTIVE COUETTE FLOW IN A VERTICAL CHANNEL WITH NON-LINEAR THERMAL RADIATION, DYNAMIC VISCOSITY AND DYNAMIC THERMAL CONDUCTIVITY EFFECTS

In this paper, we investigate steady free convective Couette flow in a vertical channel with nonlinear thermal radiation, dynamic viscosity and dynamic thermal conductivity effects. The investigation is motivated by the studies of some researchers which assumed linear thermal radiation and constant fluid properties. However, this is uncalled for; as these assumptions do not reflect true behavior of the flow. For instance; increase in temperature affects fluid viscosity, thermal conductivity thereby changing the transport phenomenon. Here; the investigation considers both the fluid viscosity and thermal conductivity to be dependent on temperature with the thermal radiation adopting nonlinear form. Due to this reasons, the associated flow equations are highly nonlinear and exhibit no analytical solution and therefore require the use of Adomian decomposition method (ADM) of solution. The attained ADM solution is then coded into computer algebra package of mathematica where results under the parameters of interest are presented and discussed. Results of the investigation show that raising the thermal radiation leads to corresponding rise in both the velocity and temperature of the fluid in the channel. Furthermore; lessening the viscosity and thermal conduction of the fluid were identified to escalate both velocity and temperature of the fluid.

Degradation mechanisms and non-linear thermal cycling effects in a high-temperature light-absorber coating

Absorber coatings in concentrating solar power (CSP) convert focused solar radiation into heat. Competitive and reliable CSP technologies require absorber coatings to be stable at high temperatures for many years of operation, and thus accelerated ageing tests are essential to evaluate and further develop these coatings. However, the ageing mechanisms are largely unknown, with previous studies mainly focusing on isothermal (IT) annealing or rapid-cycling (RC) thermal tests, not the more realistic cycle-and-hold (CH) thermal cycling caused by cloud shading. This investigation reports the effects of IT, CH and RC on degradation of Pyromark 2500 on Inconel 625. CH thermal cycling was a combination of IT (equivalent heating time at Tmax=850°C ) and RC (equivalent cycles). The results showed non-linear effects because: IT and RC samples were found to be stable (within 100 h or 1260 cycles) in terms of absorptance, despite having some differences in morphology; whereas CH samples experienced a drop in solar-weighted absorptance after 10 h (126 cycles) at Tmax followed by an increase after 100 h (1260 cycles). SEM and XRD analyses suggested that thermal cycling promoted sintering of the silica binder, producing an amorphous structure between fully formed crystalline grains, which were identified as nickel- and/or manganese-based chromite. The sintering occurred more severely for CH than RC due to holding the temperature at Tmax. Cracking was also more pronounced in CH than RC and IT, possibly due to stronger coating shrinkage. The results suggest that accelerated ageing tests should consider CH thermal cycling to better analyse coating degradation and predict its lifetime.

An exact analysis of radiative heat transfer and unsteady MHD convective flow of a second‐grade fluid with ramped wall motion and temperature

AbstractThe influence of simultaneously applied ramped boundary conditions on unsteady magnetohydrodynamic natural convective motion of a second‐grade fluid is investigated and analyzed in this study. The motion of the fluid is considered near an infinite upright plate that is nested in a porous medium subject to nonlinear thermal radiation effects. The Laplace transformation technique is utilized to acquire the exact solutions of momentum and energy equations. To effectively examine the rate of heat transfer and shear stress, the Nusselt number and skin friction coefficient are also established. The outcomes of mathematical computations are elucidated through tables and figures to highlight some physical aspects of the problem. Some limiting models of the present problem are also deduced and presented. On comparison, it is observed that the fluid exhibits lower temperature and velocity profiles under ramped boundary conditions. It is also found that wall shear stress can be controlled by choosing large values of the magnetic parameter (M) and Prandtl number (Pr). In addition, the heat transfer rate specifies inverse trends for growing values of radiation parameter (Nr) and Prandtl number (Pr), while it increases rapidly under a ramped surface condition and decreases slowly under a constant surface condition.

Optimization strategy for the velocity distribution based on tool influence function non-linearity in atmospheric pressure plasma processing

Atmospheric pressure plasma processing (APPP) is proved to be potential in the fabrication of optical elements with high efficiency and near-zero damage. However, high convergence rate in the figuring process is hard to achieve because of the tool influence function (TIF) non-linearity. Directly solved dwell time map by conventional deconvolution methods does not consider the non-linear thermal effect, which leads to significant figuring error. In this paper, the optimization strategy for TIF non-linearity based on the velocity distribution in APPP is presented. The exponential model of TIF with non-linearity is established by trench experiments. A series of simulations are also conducted to analyze the thermal effect of non-linearity on the figuring process, indicating the TIF constantly changes with velocity distribution. Two evaluation parameters, relative balance factor and velocity concentration factor, are proposed to investigate the figuring capacity of calculated velocity distribution. With two evaluation parameters, the optimization strategy of velocity distribution based on TIF selection is proposed to suppress the non-linearity. Verification experiments are carried out to validate the two optimized TIFs. The results show that high convergence is achieved to be 72.41% and 82.81% for root-mean-square value respectively, which proves the feasibility of the proposed optimization strategy.

Micropolar flow of EMHD nanofluid with nonlinear thermal radiation and slip effects

Magneto-micropolar electrically conducting nanofluid flow over a linearly stretching sheet for heat and mass transfer in the presence of convective boundary condition is considered. In the energy equation, non-linear thermal radiation and Joule heating effects are incorporated. Velocity slip condition at the solid liquid interface is also employed. In the current model viscous dissipation and mixed convection aspects are also taken into account. Non dimensional ordinary differential equations are acquired by implementing the similar transformations on the governed partial differential equations. The shooting technique is utilized along with Runga-Kutta integration scheme to tackled the differential equations numerically. All the numerical calculations are further verified with MATLAB bvp4c scheme. Graphical results are exploited to view the behavior of emerging parameters on velocity, temperature and concentration of nanofluid. In limiting case, MATLAB code is verified with a published article and a good agreement is noted. Numerical computations are performed for the local Sherwood and Nusselt number and skin friction coefficients. It is observed that the electric field is dominant over the magnetic field. The behavior of velocity profile is reserved in the absence of the electric field. Further, the nonlinear thermal radiation aggregates the temperature profile.

Discrimination between two distinct nonlinear effects by polarization-resolved Z-scan measurements.

We investigated how the Z-scan technique can be explored to distinguish two types of nonlinear refractive effects by employing two distinct laser polarizations. It is possible that pure electronic, molecular orientation and thermal nonlinear effects may occur simultaneously during light-matter interaction. We found a way to discriminate and quantify two distinct nonlinear processes from Z-scan signals measured with linear and circular polarizations. This paper provides analytical equations for nonlinear refractions and in order to test them, we carried out measurements in CS2 and in a rhodamine-B solution, where electronic and orientational, and electronic and thermal nonlinearities mixing, respectively, are present.

Inclined magnetic field effects on Marangoni flow of Carreau liquid

Marangoni convection flow of Carreau liquid by an inclined porous surface is addressed. Magnetic field is taken inclined. Non-linear thermal radiation effects are incorporated considering the Rosseland?s approximation. Runge-Kutta-Fehl?berg fourth fifth order scheme is utilized to solve the non-linear equations subject to non-linear convective boundary conditions. Non-linear expression of Nusselt number is derived. Concrete graphical description is present out for flow velocity, temperature and Nusselt number. Numerical treatment of non-linear Nusselt number is performed and analyzed.

Non-linear thermal radiation and magnetic field effects on the flow Carreau nanofluid with convective conditions

Main features of the present analysis is to investigate the MHD non-linear mixed convection flow of Carreau nanofluid. Flow is due to stretching sheet with thermal and solutal convective conditions. Intention in present analysis is to develop a model for nanomaterial. The non-linear ordinary differential systems are obtained. Homotopy algorithm leads to solutions development. Velocity, temperature, nanoparticles concentration, surface drag force, and heat and mass transfer rate are displayed and argued. It is revealed that qualitative behaviors of velocity and layer thickness are reverse for material and magnetic parameters. Temperature field and heat transfer rate are similar observation for thermal Biot numbers. Moreover qualitative behaviors of nanoparticles concentration and mass transfer rate are reverse for larger Brownian motion.

Effect of the Thermal Properties of the Substrate on the Nonlinear Photoacoustic Signal Characteristics of Opaque Media

The effect of thermal nonlinearity (TN) owing to the temperature dependence of the thermal parameters of the substrate, gas layer, and an opaque sample, as well as its black-body coefficient, on the characteristics of the nonlinear photoacoustic (PA) signal at the fundamental (FH) and second (SH) harmonics during gas-microphone reception is studied theoretically. It is shown that the frequency dependence of the FH is ~ω–1/2 and of the SH, ~ω–3/2. The dependence of the amplitude of the FH on the incident beam intensity is nontrivial and is expressed in terms of the dependence of the temperature increments of the irradiated Θ0 and back W0 sides of the sample surface on I0, while this dependence for the SH is $$ \sim {l}_0^2 $$.