A theoretical analysis of heat transfer due to particle impact

Sun, Jichao; Chen, M.M.

doi:10.1016/0017-9310(88)90085-3

Cited by 148 publications

(72 citation statements)

References 3 publications

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“…The transient heat flux of the contacting grains is approximated by the steady-state value. This assumption is discussed in [3,12] and proves to be reasonable even for collision-dominated flows, and even more so in our dense flows with sustained contacts. The thermal discrete element method involves the numerical integration of grain motion by Newton's law, considering the local force and torque balances.…”

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confidence: 99%

Thermal Transients and Convective Particle Motion in Dense Granular Materials

Rognon

Einav

2010

Phys. Rev. Lett.

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The mechanism of dry granular convection within dense granular flows is mostly neglected by current analytical heat equations describing such materials, for example, in geophysical analyses of shear gouge layers of earthquake and landslide rupture planes. In dry granular materials, the common assumption is that conduction by contact overtakes any other mode of heat transfer. Conversely, we discover that transient correlated motion of heated grains can result in a convective heat flux normal to the shear direction up to 3-4 orders magnitude larger than by contact conduction. Such a thermal efficiency, much higher than that of water, is appealing and might be common to other microscopically structured fluids such as granular pastes, emulsions, and living cells. DOI: 10.1103/PhysRevLett.105.218301 PACS numbers: 47.57.Gc, 47.55.pb, 65.20.Àw, 91.32.Jk The temperature evolution within sheared granular layers is balanced by heat production and transfer. Identifying the dominant modes of the heat transfer is therefore critical to temperature predictions. As typical with any classical fluid, the two most important modes of heat transfer during granular flow are those by conduction and convection. Heat conduction is now well understood to rely on the properties controlling the contact network: contact size, anisotropy, and heterogeneity [1][2][3][4]. Various studies examined the effect of convection on the heat transfer between the flowing granular materials and bounding walls [5]. In such cases where the wall interacts with the flow, the heat transfer is affected by the first layer of wall-contacting grains that may or may not recirculate. Moreover, the efficiency of the overall heat transfer depends on the thermal properties of the wall. Here, we examine the heat transfer that is purely intrinsic to the granular media, independent of wall properties. Intrinsic to the flow, the heat is carried by grains as they move. We term this process dry granular convection. Some heat is thus simply flowing along the mass flux. In addition to this obvious advection, in turbulent flow of water vortices develop and induce heat transfer normal to the mass flux [6]. Granular flows exhibit similar turbulent-like patterns of velocity vortices [7], leading to temperature mixing normal to the mass flux [8], but the corresponding heat flux has not been studied. Unlike water, vortice-like motion in granular media results from force chain buckling, leading to high fluctuations in local strain and kinetic energies, and thereafter, as we show, to thermal convection that increases with vertical stresses.In this Letter, we discover that dry granular convection does add a striking contribution to the overall heat transfer budget in dense granular flows. The study is based on a series of numerical experiments using thermal discrete element method [2]; the motion and the temperature evolution of the grains are simulated while they experience a plane shear flow and a temperature gradient in the direction transverse to the shear plane [ Fig. 1(a)]. ...

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confidence: 99%

Thermal Transients and Convective Particle Motion in Dense Granular Materials

Rognon

Einav

2010

Phys. Rev. Lett.

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“…Most of the available theories in this regard (Sun and Chen, 1988;Mei et al, 2012) cannot be directly applied for the current study because they are based on the Hertzian contact theory (Johnson, 1987), which does not account for the repulsive and attractive electrical forces acting on the contacting bodies. According to the previous studies, often, the conductive heat transfer between the impinging particles and HTS is insignificant (Murray, 1994a;Li et al, 2003).…”

Section: Particle Rebound Mechanism (Prm)mentioning

confidence: 99%

Heat Transfer Enhancement in a Stagnant Dielectric Liquid by the Up and Down Motion of Conductive Particles Induced by Coulomb Forces

Eslami

Esmaeilzadeh

García-Sánchez

et al. 2017

JAFM

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When charged particles are exposed to an electric field the well-known Coulomb force acts on them. In this investigation, this force is utilized to induce vertical motion of spherical steel particles submerged in a dielectric liquid. The interelectrode space of a two parallel electrode system is filled with the liquid and dispersed steel particles, which become charged after contact with the electrodes. Experiments were carried out to measure the effect of this particle motion on the heat transfer between an electrode surface and an adjacent stagnant dielectric liquid. In order to interpret the experimental data, the dynamics of particles was analytically studied for low particle volume concentrations. Experimental results demonstrate significant heat transfer enhancement on low viscosity dielectric liquids. A detailed discussion is presented on the possible mechanisms responsible for such an enhancement.

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“…First, we employ a simple model for the heat flux ĳ ij from grain i to grain j with temperatures T i and T j at their centers [15]; this simple model proves to be reasonable for collision-dominated flows, and even more so in dense flows with sustained contacts [16,17].…”

Section: Figurementioning

confidence: 99%

10,000 – A reason to study granular heat convection

Einav¹,

Rognon²,

Gan³

et al. 2013

AIP Conference Proceedings

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Abstract. In sheared granular media, particle motion is characterized by vortex-like structures; here this is demonstrated experimentally for disks system undergoing indefinite deformation during simple shear, as often imposed by the rock masses hosting earthquake fault gouges. In traditional fluids it has been known for years that vortices represent a major factor of heat transfer enhancement via convective internal mixing, but in analyses of heat transfer through earthquake faults and base planes of landslides this has been continuously neglected. Can research proceed by neglecting heat convection by internal mixing? Our answer is astonishingly far from being yes.

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A theoretical analysis of heat transfer due to particle impact

Cited by 148 publications

References 3 publications

Thermal Transients and Convective Particle Motion in Dense Granular Materials

Thermal Transients and Convective Particle Motion in Dense Granular Materials

Heat Transfer Enhancement in a Stagnant Dielectric Liquid by the Up and Down Motion of Conductive Particles Induced by Coulomb Forces

10,000 – A reason to study granular heat convection

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