# Interferometric Study of the Heat Transfer Phenomena Induced by Rapid Heating of Nickel Sheet
## 1 Introduction  
When the boundaries or the interiors of compressible mediums are exposed to a rapid temperature change, a rapid expansion of the adjacent medium will occur and generate a pressure or stress wave, just as when a piston is suddenly pushed into a gas-filled tube. In terms of heat transfer, the waves from these thermal phenomena in the boundary of a compressible fluid are called thermo-acoustic convection. The case of compressible fluids and thermal dynamic processes are closely related to each other because of local heat exchange. [PERSON] (1958) found the idea that a micro-difference in temperature can generate a mechanical reaction in the form of an acoustic wave in the rest of the fluid. [PERSON] et al. investigated the characteristics of fluid flow from this rapid heating, so called thermo-acoustic convection [PERSON] et al. (2018); [PERSON] et al. (2018), using numerical methods. They applied temperature-independent thermo-physical properties to finite difference solutions of the compressible Navier-Stokes equations for the gas dynamics. From the matched asymptotic expansions and multiple-time-scale methodology, [PERSON] (1958) and [PERSON] and [PERSON] (1958) investigated the thermo-acoustic phenomena in an enclosed ideal gas with slow and rapid boundary heating. They found that the dominant process has two physical regimes, thermo-dynamic convection on the acoustic timescale and strong conductive-convective coupling on the typical timescale for thermal diffusion, respectively. [PERSON] and [PERSON] [PERSON] and [PERSON] (2017); [PERSON] and [PERSON] (2018) established their theoretical modeling of the thermo-acoustic effect in gases, which specified that the thermo-mechanical waves, linear or nonlinear, should have an asymmetrical waveform, including a sharp front and a longtail. These are completely opposite configurations compared to previous predictions, such as those for a rounded symmetric configuration. [PERSON] et al. [8] investigated the characteristics of thermo-acoustic waves under a nitrogen-filled two-dimensional cavity in order to study how these can be developed to enhance the effective heat removal mechanism. [PERSON] and [PERSON] [9], [PERSON] and [PERSON] [10], [PERSON] et al. [11], and [PERSON] and [PERSON] [12] investigated the strong thermo-acoustic waves according to impulsive heating applied to boundary element methods (BEM). Moreover, they found that the horizontal velocity component reverses sign after reflection from the side walls, such as one-dimensional flow fields. Interferometric studies using the principle of interference of consistent light beams due to a phase difference are useful methodologies for the experimental study of thermal fluid phenomena. [PERSON] and [PERSON] [13] checked the heat transfer coefficients on a uniformly heated vertical plate using Mach-Zehnder interferometry. [PERSON] and [PERSON] [14] investigated the thermal boundary layer of a vertical flat plate using an interferometric apparatus. [PERSON] and [PERSON] [15] explained their interferometric study using laser beams for the measurement of the refractive index and the thermal phenomena of burners. [PERSON] et al. [16] experimentally investigated the incompressible flow of air over heated obstacles in a two-dimensional and horizontal channel using holographic interferometry and high-speed cinematography. [PERSON] [17] studied the convection phenomena from the heated wall of a duct using various interferometric methods like interferometry, Schlieren, and PIV (particle image velocimetry) methods with a high-speed camera. [PERSON] and [PERSON] [18] performed finite difference methods to check the forced convection phenomena in a compact mini-channel with rectangular obstacles and compared these results to the experimental results using Michelson interferometry. These technologies can be applied to various fields where temperatures are not very high. Interferometry can be an effective means for measuring three-dimensional unsteady thermal flow fields accurately.