Dissipative Effects Research Articles

Effect of low-energy ion modification of microcomposite (1-x)WO3 – xZnO ceramics on improved photocatalytic decomposition efficiency

The main purpose of this work is to study the possibility of using ionic modification of (1-x)WO3 – xZnO microcomposite ceramics in order to elevate their photocatalytic activity, as well as enhance stability to degradation during long-term use and exposure to aggressive environments. The objects of study were (1-x)WO3 – xZnO ceramics obtained by solid-phase synthesis from tungsten and zinc oxides. Moreover, according to X-ray phase analysis data, it was found that variations in the ratio of oxide components during their mechanical activation and subsequent thermal annealing result in the formation of two-phase ceramics with different contents of the zinc tungstate phase. The results of experiments on the photocatalytic decomposition of the organic dye Rhodamine B revealed that two-phase WO3/ZnWO4 ceramics have the greatest efficiency, for which ion irradiation with fluences of 1015 ––5 × 1015 leads to a growth in the decomposition efficiency from 80 to 95 %. At the same time, the dominant effect influencing the photocatalytic decomposition efficiency growth is the change in the band gap of the ceramics, associated with the accumulation of the athermal effect of energy dissipation of incident ions on the change in electron density. The results of assessment of changes in the strength and structural parameters of (1-x)WO3 – xZnO ceramics depending on the time spent in model solutions (to simulate the effects of environments with different acidity levels) indicate a positive effect of ionic modification on enhancing stability to degradation and softening as a result of the accumulation of amorphous inclusions.

Influence of thermal radiation, viscous dissipation, and joule heating on entropy generation and flow of a Maxwell hybrid nanofluid over an exponentially stretching sheet with couple stress effects

Using a numerical technique, this study explores the flow and thermal aspects of a Maxwell hybrid nanofluid across an exponentially stretched sheet. The analysis incorporates the effects of thermal radiation, viscous dissipation, Joule heating, and chemical reaction. We use the in-built MATLAB function bvp4c to successfully solve the governing equations after we convert them to ordinary differential equations. The key novelty of this work lies in employing the Maxwell hybrid nanofluid, a more complex fluid than traditional nanofluids or regular Maxwell fluids and conducting a multifaceted analysis that considers factors like couple stress, chemical reaction, and entropy generation optimization alongside flow and heat transfer. The findings demonstrate that the Maxwell parameter and the magnetic field parameter both reduce fluid velocity due to opposing forces and enhanced elasticity, respectively. The temperature profile exhibits a rise with increasing thermal radiation, volume fraction of nanoparticles, and Eckert number due to enhanced radiative absorption, improved heat transfer, and internal heat generation respectively. As the Brinkman number and volume percentage of copper nanoparticles increase, the entropy generation becomes more intense and the Bejan number decreases as a result of enhanced viscous dissipation and friction. Between the values of 0.1 and 0.7 for Maxwell parameter, the friction factor exhibits a decrement of 0.1077. The Nusselt number, signifying heat transfer efficiency, reduces with the Eckert number but increases with the radiation parameter and volume fraction of nanoparticles. Between the values of 0.1 and 0.7 for Eckert number, the friction factor exhibits a decrement of 0.1077. Lastly, a steeper concentration gradient causes the Sherwood number, which is an indication of the mass transmission rate, to rise with the Schmidt number. it is detected that the rate of heat transfer increases at a rate of 0.0721 when chemical reaction values lie between 0 and 1.8.

The effect of higher-order dissipation on solutions of the generalized korteweg-de vries equation

The effect of higher-order dissipation on solutions of the generalized korteweg-de vries equation

High-Fidelity Simulation of the Light-to-Dense Stratification Transient in the HiRJET Facility

Density stratification in a large enclosure is a crucial phenomenon to heat transfer and sustainable passive heat removal of a sodium fast reactor during reactivity transients. However, engineering turbulence models were identified to have unsatisfactory performance in predicting propagation of a stratified front. Yet, the scarcity of high-resolution data for stratification hampers the development of models. To explor e applications of leveraging direct numerical simulation (DNS) data to support turbulence model development, this work conducted DNS using NekRS to study a long stratification transient in the High-Resolution Jet (HiRJET) experimental facility. This work considers an experiment run where light fluid is injected into a tank containing a denser fluid with a relative density difference of 1.5%. Formation of the stratified layer is identified as impingement of the buoyant jet promoting mixing of the two fluids. Based on the transient statistics, transport of the concentration can be characterized by regions with dominating effects of turbulent mixing, buoyant dissipation, and molecular diffusion, respectively, as moving away from the elevation of jet impingement. Concentration near the stratified front also exhibits oscillation at Brunt-Väisälä frequency. Preliminary validation of the simulation showed encouraging agreement of the concentration distribution with the reference experiment.

Applications of partial differential equations to transient heat and mass transfer in MHD flow over a porous medium

The flow problem discussed in this research is an investigation of compressible viscous fluid in an unstable 2D MHD laminar driven vortex and stable boundary layer flow, passing a heated stretched sheet at varying speeds via a porous medium exposed to a magnetic field with viscous dissipation, thermal diffusion, thermal radiation, chemical reaction and Dufour effects. With the aid of similarity transformations, PDEs that come out in governing equations of this formulations are converted into non-linear sets of ODEs. Well-defined bvp4c technique used to numerically solve these converted equations. With use of various graphs, the consequences of different factors on the distributions of velocity, temperature and concentration were examined numerically and graphically. Physical parameters for this issue are also discussed.

Dissipative tidal effects to next-to-leading order and constraints on the dissipative tidal deformability using gravitational wave data

Dissipative tidal effects to next-to-leading order and constraints on the dissipative tidal deformability using gravitational wave data

Observation of Topological Transition in Floquet Non-Hermitian Skin Effects in Silicon Photonics.

Non-Hermitian physics has greatly enriched our understanding of nonequilibrium phenomena and uncovered novel effects such as the non-Hermitian skin effect (NHSE) that has profoundly revolutionized the field. NHSE has been predicted in systems with nonreciprocal couplings which, however, are challenging to realize in experiments. Without nonreciprocal couplings, the NHSE can also emerge in systems with coexisting gauge fields and loss or gain (e.g., in Floquet non-Hermitian systems). However, such Floquet NHSE remains largely unexplored in experiments. Here, we realize the Floquet NHSEs in periodically modulated optical waveguides integrated on a silicon photonic platform. By engineering the artificial gauge fields induced by the periodical modulation, we observe various Floquet NHSE phases and unveil their rich topological transitions. Remarkably, we discover the transitions between the unipolar NHSE phases and an unconventional bipolar NHSE phase, which is accompanied by the directional reversal of the NHSEs. The underlying physics is revealed by the band winding in complex quasienergy space which undergoes a topology change from isolated loops with the same winding to linked loops with opposite windings. Our work unfolds a new route toward Floquet NHSEs originating from the interplay between gauge fields and dissipation effects, and thus offers fundamentally new ways for steering light and other waves.

Thermal process computing in nanofluid using dissipation and squeezing constraints

AbstractThe investigation of thermal mechanisms in traditional as well as advanced fluid phases grabbed huge attention of the engineers around the globe. These fluids have a bright future in numerous fields including but not restricted to chemical, applied thermal, and heat transfer applications. Therefore, the present analysis emphasized on the development and investigation of a new nanofluid model under physical constraints like viscous dissipation, squeezing, and nanoparticle concentration effects. The fourth‐order heat transfer model is formulated using new thermophysical properties of tetra nanofluids and similar transformative functions. Then, the model was analyzed numerically and a deep discussion of the results was provided. It is noticed that the motion reduced near the bottom wall rapidly when the tetra nanoparticles concentration is taken from to and inward the sheet movement enhanced it. The fluid motion can be augmented by accelerating the top sheet in an outward direction by keeping . Moreover, the shear drag increased in the range of to and the heat transfer rate enhanced from to and to when and increased.

Piezoelectric micropump cooler for high-power electronic cooling

Micro-liquid cooling is highly effective for the thermal management of electronic chips. However, it is challenging to apply to high heat flux and compact electronic devices because of the limited cooling power and large pump volume. To address this issue, a compact piezoelectric micropump cooler (PMC) integrating a parallel piezoelectric micropump (PPMP) and a heat sink with a fluid guidance structure is designed. The flow and heat transfer performance of the PMC is theoretically optimized through a numerical coupling model considering mechanics, flow-solid heat transfer, and piezoelectric effect. Simulation results suggest that a copper electrode-PZT ratio of 1.4 increases the output flow rate of the PMC, and the design of five fluid guidance structures enhances its heat dissipation effectiveness. Based on the optimized results, the PMC prototype is manufactured employing 3D printing technology. Experimental results show that the flow rate maximum is 62 mL/min with a precision of 0.07 mL/V·min. When the flow rate of PMC increases to 50 mL/min, the temperature of a heat source with 50 W/cm2 can be reduced to 57 °C, which is comparable with the simulation value. The developed model accurately characterizes the heat transfer properties of the PMC thermal management approach, providing a valuable reference for future research. The proposed PMC is characterized by its compact size, high level of integration, and exceptional cooling performance, making it suitable for electronic cooling applications with high heat flux.

Effects of viscous dissipation, temperature dependent thermal conductivity, and local thermal non‐equilibrium on the heat transfer in a porous channel to Casson fluid

AbstractThe current paper deals with viscous dissipation effects in a permeable (or porous) channel filled with non‐Newtonian Casson fluid by considering the local thermal non‐equilibrium (LTNE) model. The dependency of the effective thermal conductivities of the solid and fluid phases on the respective temperatures has been studied along with the spatially varying Biot number. The Brinkman number Casson fluid parameter , thermal conductivity variation parameter , porosity Darcy number , and the ratio of fluid and solid phase thermal conductivities are the main governing parameters. The Darcy–Brinkman model is employed to govern the fluid flow in permeable media and the velocity profile has been obtained analytically. Moreover, the energy equations for both phases along with suitable boundary conditions are derived and solved with the fourth order boundary value solver. The findings of the current study depict that the Nusselt number increases with the increment in Casson fluid parameter and decreases with the increment in Brinkman number and thermal conductivity variation parameter. Overall, the heat transmission between the solid and fluid phases increases with the decrement in Brinkman number and thermal conductivity variation parameter. On the other hand, the heat transmission between both the phases magnifies by increasing the value of Casson fluid parameter.

A novel biomass-derived carbon@ZnO@ZnSe composites for efficient electromagnetic wave absorption

A novel biomass carbon-based ternary composite coated with ZnO and ZnSe was synthesized by activated carbonization and hydrothermal method. The composition, microstructure and electromagnetic wave (EMW) absorption performance and related mechanism of the composites were investigated in detail. The unique coating structure of lamellar ZnO and spherical ZnSe facilitates multiple reflection and scattering of EMWs, thereby enhancing the dissipation of EMW energy. Moreover, the incorporation of highly conductive ZnO and ZnSe not only enhances the polarization loss and conductivity loss of CBP@ZnO@ZnSe composites, but also improves the impedance matching, further optimizing the EMW absorption property greatly. The CBP@ZnO@ZnSe composites exhibited enhanced EMW absorption performance, characterized by a minimum reflection loss of −24.57 dB and an effective absorption bandwidth of 3.43 GHz at 2.89 mm, owing to the synergistic interplay of favorable impedance matching and attenuation ability. In addition, radar cross section simulation results further demonstrated that CBP@ZnO@ZnSe composites have good electromagnetic energy dissipation effect in practical applications. This study not only offers a simple and feasible method for preparing CBP@ZnO@ZnSe composites with excellent EMW absorption properties, but also serves as a reference for the research of ternary composites based on bio-derived carbon.

Anhysteretic strains in ferroelectric ceramics under electromechanical loading

This study investigates anhysteretic strains in PZT ceramics. The anhysteretic curves are associated with a stable balanced state of polarization in the domain structure, excluding dissipative effects related to mechanisms such as domain wall pinning. Anhysteretic measurements are representative of an -ideal- scenario in which the material would undergo no energy loss due to dissipative processes, focusing on the stable and reversible aspects of the domain configuration. The different methodologies employed to measure deformations under electromechanical loading are presented, leading to the introduction of digital image correlation (DIC) as the chosen technique, recognized for its ability to capture detailed information on transverse and longitudinal strain. The article then describes a procedure developed to obtain anhysteretic strain and anhysteretic polarisation for different levels of compressive loadings. The subsequent presentation of the results of the transverse and longitudinal strain analyses provides valuable insights into the reversible and irreversible behavior of the material. They can be used as a basis for the thermodynamical modelling approaches grounded on separating reversible and irreversible contributions or as a validation of existing models describing anhysteretic behavior. The compressive stress affects both the shape of hysteretic and anhysteretic curves. The anhysteretic curve represents a stable equilibrium in the domain structure. Compressive stress reduces strain by affecting the pinning of domain walls. These points justify the interest in studying the effect of compressive stress on the anhysteretic behavior of ferroelectrics.

Quantum Coding Transitions in the Presence of Boundary Dissipation

We investigate phase transitions in the encoding of quantum information in a quantum many-body system due to the competing effects of unitary scrambling and boundary dissipation. Specifically, we study the fate of quantum information in a one-dimensional qudit chain, subject to local unitary quantum circuit evolution in the presence of depolarizing noise at the boundary. If the qudit chain initially contains a finite amount of locally accessible quantum information, unitary evolution in the presence of boundary dissipation allows this information to remain partially protected when the dissipation is sufficiently weak, and up to timescales growing linearly in the system size L. In contrast, for strong enough dissipation, this information is completely lost to the dissipative environment. We analytically investigate this “quantum coding transition” by considering dynamics involving Haar-random, local unitary gates, and confirm our predictions in numerical simulations of Clifford quantum circuits. Scrambling the quantum information in the qudit chain with a unitary circuit of depth O(logL) before the onset of dissipation can perfectly protect the information until late times. The nature of the coding transition changes when the dynamics extend for times much longer than L. We further show that at weak dissipation, it is possible to code at a finite rate, i.e., a fraction of the many-body Hilbert space of the qudit chain can be used to encode quantum information. Published by the American Physical Society 2024

Effects of dissipation and radiation on the Jeffrey fluid flow in between nano and hybrid nanofluid subject to porous medium

AbstractThe magnetohydrodynamic (MHD) movement of fluids through a porous material has a variety of uses such as distillation towers, heat exchangers, catalytic processes, magnetic field‐based wound treatments, cancer therapy and hyperthermia. This paper explores the complex dynamics of a three‐phase flow utilizing MHD Jeffrey fluid, which sits in between nano and hybrid (molybdenum disulphide [MoS2] and multi‐walled carbon nanotubes [MWCNTs]) nanofluids. The governing differential equations are derived for the physical flow model. The equations are reduced to dimensionless equations by using dimensionless parameters. The resultant equations are solved by using the regular perturbation technique. The results are analysed for various physical pertinent parameters through 2D/3D graphs. The heat transfer rate and volume flow rate are calculated for the left and right plates. This analysis also considers how the system's overall behaviour would be affected by radiation and dissipation effects. The results indicate that the magnetic parameter, electric parameter, quadratic convective parameter, Brinkman number and Grashof number significantly affect heat transfer enhancement. Fluid velocity can be reduced using radiation parameters, porosity, electric and magnetic parameters and velocity declines by Jeffrey parameters.

Entropy generation and heat transfer analysis of unsteady micropolar magnetized hybrid-nanofluid flow over a radially stretchable permeable rotating disk with viscous and joule dissipation effects

PurposeThis study investigates the unsteady, three-dimensional radiative, micropolar hybrid nanofluid flow across the radially rotating disc in a Darcy-Forchheimer porous medium, under the influence of an applied magnetic field. The effects of viscous dissipation and Joule heating are also considered. Detailed analyses of entropy generation and the Bejan number are provided. Copper (Cu) and Titanium dioxide (TiO2) nanoparticles are modeled mathematically using a cylindrical coordinate system with engine oil as the base fluid. Both Copper (Cu) and Titanium dioxide (TiO2) nanoparticles are consider 50 %-50 %. MethodologyThe Navier-Stokes equations governing momentum, microrotation, and energy are transformed into ordinary differential equations using similarity variables. These modified equations are solved numerically using shooting approach (bvp4c). The study includes graphical representations and discussions on the impact of various controlling parameters. FindingsThe considered range for the parameters are Mn = 0.1 to 3.1, β = 0.1 to 1.3, π = 0.5 to 2.0, St = 0.1 to 1.3, K1 = S0 = A3 = 0.1 to 1.0, Bi = 0.1 to 0.4, Ec = 1.0 to 1.4, . Br = 0.10 to 0.25, α1 = 0.1 to 2.5. Results indicate that the unsteady parameter decay the velocity profile (both radial and tangential direction) and reduce the microrotation velocity in r and z direction, while enhancing the microrotational velocity in θ direction. Additionally, an increase in the stretching parameter raises the radial velocity but lowers the tangential velocity profile. The temperature profile and entropy generation increases for large values of magnetic parameter, whereas the Bejan number decreases. Similarly, tables were analyzed to illustrate the impact of varying physical parameters on the skin friction local Nusselt number. It is noted that the magnetic parameter enhance the skin friction coefficient while decline the local Nusselt number. The concentration of Copper (Cu) and Titanium dioxide (TiO2) nanoparticles is (0-6)%.

Mixed Convection Boundary Layer Flow on A Vertical Flat Plate in Al203-Ag/Water Hybrid Nanofluid with Viscous Dissipation Effects

Mixed Convection Boundary Layer Flow on A Vertical Flat Plate in Al203-Ag/Water Hybrid Nanofluid with Viscous Dissipation Effects

Computation of SWCNT/MWCNT-doped thermo-magnetic nano-blood boundary layer flow with non-Darcy, chemical reaction, viscous heating and Joule dissipation effects

CNTs have been shown to exhibit exceptional electrical and thermal conductivities, chemical and mechanical stability and physiochemical reliability in wide-ranging applications covering biomedicine, energy and aerospace. Motivated by emerging applications in nano-drug delivery in medicine and radiative ablation therapy, a steady-state mathematical model is established for magnetohydrodynamic boundary-layer transport of chemically reactive carbon nanotubes (CNTs)-doped electrically conducting blood along a porous stretching wall of a blood vessel. Multiple and single walls CNTs are considered using the model developed by Xue (2005). Heat generation, radiative flux, wall mass (concentration) slip, viscous heating and Joule magnetic dissipation are incorporated. Chemical reaction effects are addressed utilizing homogenous first-order model. The Darcy-Forchheimer drag force model is utilized for bulk matrix and inertial drag effects in the porous medium. Radiative heat-transport is studied considering Rosseland's diffusion model. The governing partial differential conservation equations for mass, momentum, energy and species are formulated in a two-dimensional Cartesian coordinate system with allied wall and free-stream boundary conditions. Via scaling transformations, a nonlinear boundary value problem is derived. Numerical computations are achieved through bvp4c scheme. The impact of selected parameters on dimensionless quantities (velocity, temperature, concentration, skin friction, local Nusselt and Sherwood numbers) are computed and elaborated through tables and graphs. A good correlation of the numerical solutions with earlier simpler models from the literature is included. The simulations show that with augmentation in Hartmann magnetic number and Forchheimer inertial drag number, significant damping in the nano-doped blood flow is produced for both SWCNTs and MWCNTs. Temperature is elevated with increment in dissipation effect i. e. Eckert number. Higher values of mass (solutal) slip parameter induce a depletion in the concentration. Nusselt number i. e. heat transfer rate to the blood vessel wall is improved with greater values of solid volume fraction for both CNTs. The present model is relevant to radiative ablation therapy combined with nano-medical treatments in blood vessels wherein constant mechanical loading via blood pressure and flow can elevate internal stresses (circumferential wall stress and endothelial shear stress) and induce morphological alterations in blood vessel wall (stretching) and endothelium in conjunction with biochemical reactions.

Regularity for a Fractional Liquid Crystal Model with Anomalous Dissipation and Thermal Effects

Regularity for a Fractional Liquid Crystal Model with Anomalous Dissipation and Thermal Effects

Dissipative fracton superfluids

We present a comprehensive study of hydrodynamic theories for superfluids with dipole symmetry. Taking diffusion as an example, we systematically construct a hydrodynamic framework that incorporates an intrinsic dipole degree of freedom in analogy to spin density in micropolar (spinful) fluids. Subsequently, we study a dipole condensed phase and propose a model that captures the spontaneous breaking of the U(1) charge. The theory explains the role of the inverse Higgs constraint for this class of theories, and naturally generates the gapless field. Next, we introduce finite temperature theory using the Hamiltonian formalism and study the hydrodynamics of ideal fracton superfluids. Finally, we postulate a derivative counting scheme and incorporate dissipative effects using the method of irreversible thermodynamics. We verify the consistency of the dispersion relations and argue that our counting is systematic.

Pfaffian solutions and nonlinear dynamics of surface waves in two horizontal and one vertical directions with dispersion, dissipation and nonlinearity effects

This study delves into the exploration of the (3+1)-dimensional generalized nonlinear fractional Konopelchenko–Dubrovsky–Kaup–Kupershmidt (GFKDKK) system, a crucial nonlinear evolution equation governing wave motion across various physical domains. The core aim is to devise innovative analytical solutions for this system employing the Khater III technique and an enhanced Kudryashov methodology integrated with the conformable fractional derivative.The GFKDKK system holds pivotal significance in modeling and comprehending diverse scientific phenomena, ranging from fluid dynamics to plasma physics and nonlinear optics. This research endeavors to harness the potential of the Khater III technique and the updated Kudryashov approach to offer fresh analytical insights into nonlinear fractional differential equations, thus enriching the existing knowledge base in this domain.The attained solutions furnish invaluable insights into the dynamics of the system and its potential applications, thereby facilitating the development of effective numerical simulations and analytical frameworks. The study’s significance lies in its contribution to the ongoing exploration of nonlinear fractional differential equations and their practical implications across various industries.In conclusion, the research affirms the efficacy of the Khater III method and the enhanced Kudryashov technique, complemented by the conformable fractional derivative, in obtaining analytical solutions for the (3+1)-dimensional GFKDKK system. The novelty lies in the application of these methodologies to this specific system, resulting in the discovery of new analytical solutions that enhance our understanding of its behavior and characteristics.