Thermal waves emitted by moving sources and the Doppler effect

Voti, R. Li; Bertolotti, M.

doi:10.1016/j.ijheatmasstransfer.2021.121098

Cited by 11 publications

(6 citation statements)

References 31 publications

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“…Here, we start by assuming that the propagated thermal field satisfies the plane wave solution T = T ( x , ω) e − i ω t + T 0 , where T ( x , ω), t , ω, and T 0 denotes the complex amplitude, time, oscillation frequency, and reference temperature, respectively. [ 40,41 ] Then the wavevector can be derived accordingly, which helps describe the evanescent characteristics of thermal waves. For v ≠ 0, the wavevector is split into k + and k − (Figure 1c), depending on whether it travels with or against the convection (Figure S1, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Nonreciprocal Heat Circulation Metadevices

Ju,

Cao,

Wang

et al. 2023

Advanced Materials

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Thermal nonreciprocity typically stems from nonlinearity or spatiotemporal variation of parameters. However, constrained by the inherent temperature‐dependent properties and the law of mass conservation, previous works have been compelled to treat dynamic and steady‐state cases separately. Here, by establishing a unified thermal scattering theory, the creation of a convection‐based thermal metadevice which supports both dynamic and steady‐state nonreciprocal heat circulation is reported. The nontrivial dependence between the nonreciprocal resonance peaks and the dynamic parameters is observed and the unique nonreciprocal mechanism of multiple scattering is revealed at steady state. This mechanism enables thermal nonreciprocity in the initially quasi‐symmetric scattering matrix of the three‐port metadevice and has been experimentally validated with a significant isolation ratio of heat fluxes. The findings establish a framework for thermal nonreciprocity that can be smoothly modulated for dynamic and steady‐state heat signals, it may also offer insight into other heat‐transfer‐related problems or even other fields such as acoustics and mechanics.

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Section: Resultsmentioning

confidence: 99%

Nonreciprocal Heat Circulation Metadevices

Ju,

Cao,

Wang

et al. 2023

Advanced Materials

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“…First, convection can change the heat transfer efficiency; second, convection exhibits a preference for heat flux direction; and finally, convection could carry oscillating temperature fields. By introducing convection, the original parabolic diffusion equation describing the macroscopic thermal conduction can be modified into the hyperbolic convection‐diffusion equation, [ 27 ] hence the temperature field carried by convection could imitate many physical phenomena in wave systems. Comprehensive understandings of these emerging works are indispensable for more advanced heat manipulation.…”

Section: Introductionmentioning

confidence: 99%

Convective Thermal Metamaterials: Exploring High‐Efficiency, Directional, and Wave‐Like Heat Transfer

et al. 2023

Advanced Materials

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Convective thermal metamaterials are artificial structures where convection dominates in the thermal process. Due to the field coupling between velocity and temperature, convection provides a new knob for controlling heat transfer beyond pure conduction, thus allowing active and robust thermal modulations. With the introduced convective effects, the original parabolic Fourier heat equation for pure conduction can be transformed to hyperbolic. Therefore, the hybrid diffusive system can be interpreted in a wave‐like fashion, reviving many wave phenomena in dissipative diffusion. Here, recent advancements in convective thermal metamaterials are reviewed and the state‐of‐the‐art discoveries are classified into the following four aspects, enhancing heat transfer, porous‐media‐based thermal effects, nonreciprocal heat transfer, and non‐Hermitian phenomena. Finally, a prospect is cast on convective thermal metamaterials from two aspects. One is to utilize the convective parameter space to explore topological thermal effects. The other is to further broaden the convective parameter space with spatiotemporal modulation and multi‐physical effects.

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“…The structure of the paper is the following: in the second paragraph we will discuss an old question debated originally by Planck and Einstein concerning the general meaning of the temperature of a moving body [16]. In the third paragraph we will illustrate briefly a previous model [17], published few years ago, which discussed a thermal analogue of the Doppler effect. In the fourth paragraph we will show how to deduce a rotational frequency shift for thermal fields propagating on rotating conductors, identical to those observed with acoustic waves which proved the existence of Rotational Superradiance.…”

Section: Introductionmentioning

confidence: 99%

A Thermal Analogue of the Zel’Dovich Effect

Bei

2023

JAMP

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We analyze in this work anisotropic heat conduction induced by a harmonically oscillating laser source incident on rotating conductors, exploiting an analogy with an effect discovered long ago, called the Zel'dovich effect. We re-covered the main results of a recently published paper that predicts the translational Doppler frequency shift of a thermal wave induced on a sample moving with uniform rectilinear motion. We extend then this framework to take into account the frequency shift of a thermal field propagating on a rotating platform. We show that it coincides with the rotational frequency shift which has been recently observed on surface acoustic waves and hydrodynamic surface waves, called rotational superradiance. Finally, we use an analogy with the Tolman effect to deduce a simple estimate of the average temperature gradient induced by rotation, showing the existence of a new cooling effect associated with heat torque transfer.

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Thermal waves emitted by moving sources and the Doppler effect

Cited by 11 publications

References 31 publications

Nonreciprocal Heat Circulation Metadevices

Nonreciprocal Heat Circulation Metadevices

Convective Thermal Metamaterials: Exploring High‐Efficiency, Directional, and Wave‐Like Heat Transfer

A Thermal Analogue of the Zel’Dovich Effect

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