Thermal Wave Research Articles

Generalized piezothermoelasticity of hollow spheres under thermal shock using Lord–Shulman theory

Present investigation deals with the response of a piezoelectric hollow sphere that is subjected to sudden thermal shock. Loading and boundary conditions are assumed to be symmetric so the response of the sphere is also considered to be symmetric. The governing equations of the vessel are obtained which are three in number. These equations include the equation of motion, the energy equation and the Maxwell equation. The energy equation is established in the framework of single relaxation time theory of Lord and Shulman. The established equations are written in terms of temperature change, radial displacement, and electric potential. These equations are provided in a dimensionless presentation for the sake of generality. After that with the aid of the generalized differential quadrature method, the established equations are discreted. Also Newmark time marching scheme is applied to trace the radial displacement, electric potential, and temperature change in time domain. Novel numerical results are then provided to explore the propagation and reflection of electrical, thermal and mechanical waves in a hollow sphere. It is shown that temperature wave propagates with finite speed within the framework of the Lord–Shulman theory.

Latitudinal Propagation of Thermal Rossby Waves in Stellar Convection Zones

Using an analytic model, we derive the eigenfrequencies for thermal Rossby waves that are trapped radially and latitudinally in an isentropically stratified atmosphere. We ignore the star’s curvature and work in an equatorial f-plane geometry. The propagation of inertial waves is found to be sensitive to the relative direction of the wavevector to the zonal direction. Prograde propagating thermal Rossby waves are naturally trapped in the radial direction for frequencies above a critical threshold, which depends on the angle of propagation. Below the threshold frequency, there exists a continuous spectrum of prograde and retrograde inertial waves that are untrapped in an isentropic atmosphere but can be trapped by gradients in the specific entropy density. Finally, we discuss the implications of these waves on recent observations of inertial oscillations in the Sun, as well as in numerical simulations.

Elasto-thermoelectronic diffusion waves with changing thermal conductivity and thermal heating of microtemperature semiconductor

This paper presents a theoretical investigation of linear thermal conductivity temperature-dependent coupled elasto-thermoelectronic diffusion (ETD) waves in a micro-temperature semiconductor, specifically focusing on the effects of photo-excited processes. The governing equations are formulated for a semi-infinite silicon wafer, which serves as a semiconductor material. The explicit study of the strong coupling between the equations governing elastic wave transport, carrier (plasma) transport, and thermal wave transport is conducted in the presence of microtemperature influence. The electron–hole interaction is obtained within the framework of the ETD theory. Laplace transform is used to resolve the governing equations in a non-dimensional framework for thermoelastic and electronic deformation in one-dimensional (1D) scenarios. The present study employs the proposed model to analyze the impact of ramp-type heating on a stationary plane of unbounded semiconductor material. Thermoelastic electronic coupling is found to be affected by the presence of variable thermal conductivity and microtemperature parameters.

Feature Recognition in Quadratic Frequency Modulated Thermal Wave Imaging for Subsurface Defect Detection in Fiber-Reinforced Polymers

Feature Recognition in Quadratic Frequency Modulated Thermal Wave Imaging for Subsurface Defect Detection in Fiber-Reinforced Polymers

Thermal shock fracture of honeycomb-based porous thermoelectric materials with non-Fourier heat conduction

Compared with dense thermoelectric materials (TEMs), the auxetic honeycomb porous TEMs can enhance mechanical performance and energy conversion efficiency. The Fourier heat conduction law becomes unavailable due to the thermal wave speed in the porous TEMs is limited. Considering the non-Fourier law, this paper analyzes the thermal shock fracture characteristics of the porous TEMs bonded to an elastic substrate. A theoretical model for the effects of non-Fourier heat conduction, thickness of TME, shape and dimensions of honeycomb cell on strength failure and fracture failure is proposed. The analysis demonstrates that the maximum thermal stresses in the porous TEMs are underestimated without considering the non-Fourier heat conduction. The stress level in the auxetic honeycomb-based TEMs is much smaller than that in the traditional honeycomb TEMs with the positive Poisson's ratio architecture. It is found that a thicker TEM, a bigger relative density and a larger length ratio of the horizontal to the inclined strut can result in a smaller thermal stress. Based on the strength and fracture criterions, the envelope of safety angle between the horizontal and the inclined strut is identified. The simplified expressions of the safety angle envelope versus the applied thermal load are given.

Effect of Magnetic and Thermal Parameters on the Reflected Waves in Generalized Magneto Thermoelastic Materials

The present paper is concerned with the problem of reflection of homogeneous plane waves from the free surface of a generalized magneto thermoelastic half-space. The phase speeds of corresponding to longitudinal, transverse and thermal waves are obtained and are independent of angle of propagation. The amplitude and energy ratios corresponding to the reflected waves are obtained theoretically and numerically with the help of boundary conditions. The effects of magnetic and thermal parameters on the reflected waves are examined. The results hold the conservation law of energy.

Bioanalytical sensors using the heat-transfer method HTM and related techniques.

This review provides an overview on bio- and chemosensors based on a thermal transducer platform that monitors the thermal interface resistance R th between a solid chip and the supernatant liquid. The R th parameter responds in a surprisingly strong way to molecular-scale changes at the solid-liquid interface, which can be measured thermometrically, using for instance thermocouples in combination with a controllable heat source. In 2012, the effect was first observed during on-chip denaturation experiments on complementary and mismatched DNA duplexes that differ in their melting temperature. Since then, the concept is addressed as heat-transfer method, in short HTM, and numerous applications of the basic sensing principle were identified. Functionalizing the chip with bioreceptors such as molecularly imprinted polymers makes it possible to detect neurotransmitters, inflammation markers, viruses, and environmental pollutants. In combination with aptamer-type receptors, it is also possible to detect proteins at low concentrations. Changing the receptors to surface-imprinted polymers has opened up new possibilities for quantitative bacterial detection and identification in complex matrices. In receptor-free variants, HTM was successfully used to characterize lipid vesicles and eukaryotic cells (yeast strains, cancer cell lines), the latter showing spontaneous detachment under influence of the temperature gradient inherent to HTM. We will also address modifications to the original HTM technique such as M-HTM, inverted HTM, thermal wave transport analysis TWTA, and the hot-wire principle. The article concludes with an assessment of the possibilities and current limitations of the method, together with a technological forecast.

MXene based aerogel composite with thermal camouflage and electromagnetic wave absorption performance

In this study, the electrospinning method was successfully applied to the preparation of Ti3C2 @Fe3O4 @rGO aerogel. To accomplish comprehensive advantages, reduced graphene oxide (rGO), Ti3C2 MXene nanosheets and Fe3O4 nanoparticles were suitably combined. The prepared Ti3C2 @Fe3O4 @rGO aerogel with superior high-temperature indoor/outdoor thermal camouflage performance: wide camouflage temperature range (from room temperature to over 200 ℃), large reduction in radiation temperature (exceeding 120 ℃ for objects with temperatures over 200 ℃). Meanwhile, the electromagnetic interference (EMI) shielding efficiency of the Ti3C2 @Fe3O4 @rGO in the X-band reaches 50 dB which means that it can shield more than 99.9 % of the incident electromagnetic waves. In conclusion, the successful preparation of Ti3C2 @Fe3O4 @rGO provides an effective strategy for the design of high-temperature thermal camouflage and microwave absorber in the future.

Lateral heat flux reduction using a lock-in thermography compensation method

The naturally diffusive heat flow in solids often results in differences in surface temperatures. Active thermography (AT) exploits such differences to gain information on the internal structure, morphology, or geometry of technical components or biological specimens. In contrast to sound or light waves, thermal waves are lossy; consequently, it is difficult to interpret measured 2D temperature fields. Most AT evaluation methods are based on 1D approaches, and measured 3D heat fluxes are frequently not considered, which is why edges, small features, or gradients are often blurred. Herein, we present a method for reducing the local temperature gradients at feature areas and minimizing the induced lateral heat flux in optical lock-in thermography (LT) measurements through spatial- and temporal-structured heating. The vanishing lateral gradients convert the problem into a 1D problem, which can be adequately solved by the LT approach. The proposed compensation method can bypass the blind frequency of LT and make the inspection largely independent of the excitation frequency. Furthermore, the edge sharpness and separability of features are improved, ultimately improving the feature-detection efficiency.

Computational biomedical simulations of Cattaneo Christov heat flux model in diseased arteries with a combination of aneurysm and stenosis

In present article, computational biomedical simulations of Cattaneo Christov heat flux model in diseased arteries with a combination of aneurysm and stenosis is implemented in order to investigate its effects on the blood flow across the cylinder, the magnetic field is also applied. Stenosis causes a decrease in cross sectional area of the vascular lumen and is produced by the addition of fats and other hydrocarbons below the vascular endothelium of the arterial wall. For the heat transfer, Fourier law has parabolic nature which represents the temperature field moves fast with initial disturbance and spreads in whole substance. Cattaneo introduced additional parameter of relaxation time in the classical Fourier's law to get around this problem, creating the option of carrying heat by the motion of thermal waves with a slow pace. Using a mild stenotic assumption, we normalized the bi-directional, non-linear momentum and energy equations and reduce them to a unidirectional flow. Using the finite difference method, we discretized the associated partial differential equations. The resulting algebraic problem is solved numerically by using Matlab software. As a result, numerical solutions are obtained and these results are used to test the effects of different emerging parameters on flow pattern that are demonstrated in velocity, temperature, wall shear stress and flow rate profiles. The cross-sectional behavior of the blood flow patterns is also developed using streamlines for general readers.

Growth mechanism and structure regulation of super-elastic SiC aerogels for thermal insulation and electromagnetic wave absorption

High-performance silicon carbide (SiC) aerogels with excellent high-temperature resistance and high porosity are highly desirable in the fields of thermal insulation and adsorption. However, constructing a super-elastic SiC aerogel and controlling its properties is still a significant challenge. To better regulate its properties, it is necessary to clarify its reaction and growth mechanism. Here, we propose an in-situ reactive growth strategy to prepare super-elastic SiC aerogels. The obtained aerogels can withstand 80 % deformation and exhibit an ultra-low thermal conductivity of 0.024 W·m−1 K−1. Furthermore, the aerogel shows a superior electromagnetic wave (EMW) absorption performance with a minimum refection loss (RLmin) value of – 40.7 dB. More importantly, we reveal the mechanism of the reaction and growth of SiC crystal. The growth process of SiC crystal can be divided into three stages: pyrolysis, nucleation and growth. Based on understanding the growth mechanism, we can further regulate the structures of SiC crystals by controlling the sintering time, including sea urchin-like, nanorod-like, nanowire-like and slub-like shapes. This study provides a new idea for preparing super-elastic SiC aerogel and regulating its structure.

Three-Dimensional Simulation of Melt Convection and Oxygen Transport in CZ-Si Crystal Growth with Cusp Magnetic Fields

The application of magnetic fields has become a standard control technique in the CZ-Si growth industry. To investigate the impact of cusp-shaped magnetic fields (CMF) on heat and mass transfer in the melt, a series of transient three-dimensional simulations were conducted for the growth of a 100 mm CZ-Si crystal with a cylindrical crucible. The turbulent melt motion was modeled using the large eddy simulation (LES) method. Six configurations of CMF with various zero-Gaussian plane (ZGP) positions were examined and numerically compared. The computed results showed that different ZGP positions resulted in distinct types of melt convection, buoyant plumes, and thermal waves. Additionally, it was observed that the studied CMF configurations effectively reduced oxygen dissolution from the crucible wall along with oxygen impurity incorporation into the crystal. These findings demonstrate the potential for precise control of the heat and mass transfer process in CZ-Si growth through the application of suitable CMF.

Numerical analysis of non-Fourier heat conduction dynamics in the composite layer

This paper presents the numerical analysis of non-Fourier heat conduction in thin composite layers under asymmetrical boundary conditions. In the thermal barriers such as steam and gas turbine blades, thin film coating are used to protect the blade from thermal damage. The coating on the blades are very short in length. Heat conduction across thin composite layer with short time is examined using a finite element approach. With this very small duration with the finite speed of the thermal wave, the Fourier mode of heat conduction is disappeared due to the infinite speed of the thermal wave assumption. Therefore, analyzing the non-Fourier heat conduction in thin layers is essential. The developed model is executed in Python using Newmark's scheme and the constant average acceleration method to predict the temperature variation and temperature contours. The present model is validated with an experimental and numerical solution with good agreement. Besides, the temperature distribution across the composite layer with the entire length of the substrate and the coating for different thermal conductivity values, thermal diffusivity, and relaxation time are examined. It is noted that when the dimensionless

Generalized continuum methodologies in acoustics: Selected case studies

Three problems from acoustics theory are considered using both analytical and numerical methods. Each problem involves the use of a particular generalized continuum (GC) formulation. In the first, mechanical and thermal plane waves in gases wherein the specific internal energy is described by the modified internal energy model are analyzed; in the second, vertically-propagating acceleration waves in a dusty, constant lapse rate, atmosphere are investigated using the Laplace transform; and, in the third, dispersed shocks in gases wherein viscous stresses are described by the Stokesian fluid relation are examined under the traveling wave assumption. The presentation concludes with a listing of possible follow-on studies involving GC-based model systems.

Thermocapillary oscillations in liquid thin films: Interplay of substrate topography and thermal wave

Liquid flows over patterned and/or contoured substrates is utilized in many practical applications e.g., lubrication flow in MEMS (micro-electromechanical systems) /NEMS (nano-electromechanical systems) devices, cell sorting operations in biology, etc. The topological gradients in such geometries induce thermal gradients, which in turn generates Marangoni hydrodynamics. Here, we theoretically showcase the interplay of substrate topology, imposed wavy temperature stimulus, and chemically patterned wall slip to generate thermo-capillarity in thin liquid films. We obtain analytical solutions for the thermal and the hydrodynamic fields for low Marangoni Ma and Reynolds Re number thermocapillary effect. Vorticity is observed to generate and transport at the liquid-gas interface, and further transported to the bulk film by vertical diffusion and convection. We also study further to understand the significance of different geometric and physical parameters on the Marangoni thermo-fluid-dynamics. Interplay of constructive and destructive interference between the wave forms of the substrate topology and imposed periodic thermal stimulus may yield maximum interfacial temperature gradients and strong thermo-capillarity. It is also observed that the lower values of system Biot number Bi enables better diffusion of heat from the patterned substrate to obtain stable thermo-capillarity. Further, the presence of optimal slip patterning allows for stronger and tuned circulations in the liquid film.

Advanced multifunctional IGBT packing materials with enhanced thermal conductivity and electromagnetic wave absorption properties

Insulated-Gate Bipolar Transistors (IGBT) face limitations in high-frequency electronic applications due to heat accumulation and electromagnetic interference issues. To address these challenges, it is crucial to develop packing materials with excellent electromagnetic interference immunity and heat dissipation properties. In this research, a novel epoxy-based packing material (MDCF@C-ZrO2/EP) with high electromagnetic wave absorption and exceptional thermal transport properties was produced by employing a unique three-dimensional carbon structure-induced nanomaterial dispersion strategy. In particular, the three-dimensional MDCF structure effectively prevents packing agglomeration and fosters the formation of an abundant hetero-interface between MDCF and C-ZrO2, leading to improved impedance matching and enhanced electromagnetic wave dissipation capabilities. Remarkably, even at a mere 5 wt% filling level, the material demonstrates an impressive reflection loss value of −58.92 dB and a wide effective absorption bandwidth of 6.68 GHz, effectively covering the entire Ku-band. Additionally, the 3D MDCF@C-ZrO2 significantly enhances the phonon transport path and elevates the thermal conductivity of pure epoxy resin by an impressive ∼ 150%. As a result, this innovative research holds tremendous potential in enabling the application of IGBTs in high-power and high-frequency electronic components, while also contributing to the advancement of next-generation wireless communications and smart devices.

Nearshore ice complex breakup is controlled by a balance between thermal and mechanical processes

AbstractShore ice is an important facet of cold‐climate coastal geomorphology yet is generally understudied in comparison to other aspects such as nearshore hydrodynamics. Climate change is resulting in more dynamic shore ice regimes (i.e., shortened ice season and multiple freeze–thaw cycles); thus, a clear understanding of the role of shore ice in coastal geomorphic evolution is needed. The presence of shore ice is generally thought to provide the coast a protective buffer from storm waves though some studies have indicated enhanced nearshore erosion and sediment transport associated with ice development. This is particularly apparent during the breakup phase of shore ice as sediment can be scoured from the bed, deposited in place, or transported offshore. Given this, understanding the mechanics of shore ice breakup is critical. This study documents the first combined field and laboratory evaluation of the physical conditions leading to shore ice breakup, detailing the complex interplay between thermal and mechanical processes in ice deterioration. Through a wave tank experiment as well as field observations, wave impacts alone are shown to be unlikely to cause breakup of shore ice and thermal weakening is required. This has important implications both for predicting when ice will break up as well as for identifying potential nearshore sediment transport pathways. If ice breaks up entirely from thermal degradation, then sediment is likely to be deposited in place, whereas if ice breaks up from a combination of thermal degradation and wave impact, then sediment can be redistributed across the shoreface. Monitoring of meteorological conditions during ice breakup can likely be used as a first‐order predictor of geomorphic changes resulting from shore ice deterioration.

Hyperbolic Conduction and Radiation Heat Transfer in Axisymmetric Cylinders with Variable Properties

This work investigates the combined mode of hyperbolic heat conduction and radiation transfer in a one-dimensional axisymmetric cylinder filled with absorbing, emitting, and scattering media. The volumetric radiation is investigated thanks to the semianalytic solution of the matrix formulation of the spherical harmonics equations PN. The governing hyperbolic energy equation is solved using the finite volume method (FVM) with Roe’s correction of interface fluxes in order to enhance the performances of the method, and the lattice Boltzmann method (LBM) has been designed for comparisons. The effects of the parameters such as constant and spatial-dependent scattering albedos, temperature-dependent thermal conductivity, heat-generated sources, extinction, and the conduction–radiation parameter on both the temperature and heat flux distributions for steady and transient states within the medium are examined. The results of the present work are in excellent agreement with those available in the literature. The PN−FVM results are also compared to those obtained with the PN−LBM combination, and excellent agreement is obtained. These results show that the mentioned parameters have a significant effect on both the temperature profiles and the hyperbolic sharp wave front. This study also shows that the proposed layered approach is an efficient, fast, and accurate solution method for radiative analysis in inhomogeneous media, whereas the Roe’s correction of interface fluxes in the FVM is suitable to accommodate a thermal wave front in non-Fourier analysis.

Thermally driven hybrid metastructure for multi-functional surface acoustic wave engineering

Acoustic wave engineering through solid mediums are essential for improving or optimizing the performances of various platforms, such as biomedical and industrial applications. Metamaterials or metasurfaces have been recently developed to artificially manipulate the wave propagation passing through mediums. However, they only conduct one fixed function passively, determined by the structure design for the particular wavelength, and their fabrication involves high-cost and complex procedures. Here, we report a thermally driven hybrid metastructure (HMS) for actively controlling surface acoustic waves. The HMS is designed as the layered structure of a thermoresponsive polymer (TP), thermal metamaterials (TMs) and an intermediate layer (IL) made of silica aerogel. For providing multi-functions, TPs conduct the considerable elastic modulus changes and corresponding wave manipulation at a certain glass transition temperature while TMs enable the programmed heating configuration, and the IL mitigates thermal and acoustic wave interference. By introducing the IL, the entire energy of the propagating wave is captured at the interface and interference between the wave and thermal energy is prevented, which directly reflects the temperature control through the TMs into the TP heating configuration. Versatile functions of programmable wave engineering including omnidirectional wave focusing-collimation through modified Luneberg lenses, dual-functioning focusing-bifurcation, and double refraction through 3-phase wave steering are demonstrated using the proposed HMS implemented by the temperature gradient design of TMs. This work will inspire tunable and scalable platforms for active controls of wave propagation enabled by thermal energy as a driving force.

Pre-landing Assessment of the Surface and Shallow Subsurface Thermal Setting of Mare Crisium of the Moon for the Heat Flow Measurement Planned on the Blue Ghost 1 Mission

In 2024, under NASA’s Commercial Lunar Payload Services initiative, a robotic lander will touch down in Mare Crisium of the Moon and deploy a heat flow probe. Ideally, the probe should penetrate the regolith deep enough (1.5–2 m) to avoid the influence of insolation, but it is a major challenge to excavate such a hole on a robotic mission. The present study assesses the insolation-induced temperature fluctuation in the shallower subsurface of the landing site in case the heat flow probe does not reach past that depth. The assessment was based on a newly constructed, one-dimensional heat conduction model, which accounted for the history of solar heat intake at the landing site for the past 100 yr. The thermal properties of the subsurface regolith of the model were constrained by the previous surface temperature observations by flyovers of NASA’s Lunar Reconnaissance Orbiter and the subsurface thermal measurement data from Apollo 17. The model showed that the amplitude of the insolation-induced annual subsurface temperature fluctuation is modulated by the 18.6 yr period precession of the Moon. The model also showed that the amplitude of this annual wave would be at (or close to) its minimum in 2024, when the mission would take place. Even though the thermal wave may be felt at depths greater than 1.5 m, because of its small amplitude, the thermal gradient in the depth range from 1 to 1.5 m would be within several percent of the gradient representative of the endogenic heat flow.