Photophoresis of aerosol particles in the free molecular and slip-flow regimes

Mackowski, Daniel W.

doi:10.1016/0017-9310(89)90233-0

Cited by 105 publications

(78 citation statements)

References 16 publications

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“…2 pp. 85-103 96 Appendix A for the cylinder (Owen et al 1981;Benincasa et al 1987;Sun et al 2005;Liu et al 2010) and a typical but similar formulism for the sphere (Bohren and Huffman 1983;Mackowski 1989;Allen et al 1991). For a particle of high absorptivity, as shown in Figure 7a, the photophoretic velocity increases with an increase in the value of the particle size parameter  / π 2 a as expected for both cases of cylindrical and spherical particles with a fixed value of * k .…”

Section: Photophoretic Velocitysupporting

confidence: 54%

“…85-103 87 Recently, the effect of thermal stress slip, incorporating with the effects of the frictional slip, thermal creep, and temperature jump, at the particle surface on the thermophoresis and photophoresis of an aerosol sphere was analyzed Soong et al 2010;Chang and Keh 2012). The thermophoretic and photophoretic forces exerted on the particle obtained from these analyses were found to agree better with experimental data in comparison with those predicted by Brock (1962) and Mackowski (1989) excluding the effect of thermal stress slip. It is widely noticed that aerosol particles are generally non-spherical and exploration of effects of particle shape on thermophoresis is needed (Leong 1984;Williams 1986;Keh and Ou 2004;Keh and Chang 2009;Wang and Keh 2010;Chen and Keh 2014).…”

Section: Introductionmentioning

confidence: 96%

“…Here, T ,  , , and k are the temperature, mass density, viscosity, and thermal conductivity, respectively, of the gas, to Equation (1) as a boundary condition for the fluid velocity v and considering the effect of temperature jump at the particle surface, Brock (1962) determined the thermophoretic velocity of an aerosol sphere in a constant imposed temperature gradient, whereas Reed (1977) and Mackowski (1989) obtained the photophoretic velocity of a spherical particle illuminated by an intense light beam. These analyses have been extended to the thermophoresis and photophoresis of non-spherical aerosol particles (Keh and Tu 2001;Chang and Keh 2010a,b).…”

Section: Introductionmentioning

confidence: 99%

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Thermophoresis and Photophoresis of an Aerosol Cylinder with Thermal Stress Slip

Chang¹,

Keh²

2017

AJHMT

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The thermophoresis and photophoresis of a circular aerosol cylinder normal to its axis in the slip-flow regime (at moderately small Knudsen number) are analyzed with thermal creep, temperature jump, frictional slip, and thermal stress slip at the particle surface. The conservation equations of heat and momentum governing the system at negligible Peclet and Reynolds numbers are solved analytically for the temperature distribution inside and outside the particle and the flow field in the surrounding fluid, and explicit formulas for the thermophoretic and photophoretic velocities of the particle are obtained. The effects of the relative size and optical properties of the particle on its photophoresis are examined from evaluating the heat source function within the particle. It is found that the particle velocities decrease with an increase in the thermal conductivity of the particle relative to the gaseous medium and the effect of thermal stress slip is significant for the case of not too small Knudsen number. The effect of thermal stress slip can augment or reduce the thermophoretic mobility of the particle, depending upon the characteristics of the particle and ambient fluid, but always increases its photophoretic mobility. For specified characteristics of the system, the thermophoretic mobility of an aerosol cylinder is smaller than that of a sphere because of its smaller specific surface area, whereas the photophoretic mobility of a cylindrical particle can be greater or smaller than that of a spherical one.

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Section: Photophoretic Velocitysupporting

confidence: 54%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Thermophoresis and Photophoresis of an Aerosol Cylinder with Thermal Stress Slip

Chang¹,

Keh²

2017

AJHMT

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“…It should also be mentioned that particles can experience negative photophoresis, which means that particles can be attracted by light. However, this is restricted to the smallest particles, roughly below 10 µm in size (Mackowski 1989;Rohatschek 1985). The fraction of the disk made up of such small particles (which exhibit either negative photophoresis or no photophoresis) might delay the clearing of the disk until larger particles have grown.…”

Section: Caveats and Future Workmentioning

confidence: 99%

The photophoretic sweeping of dust in transient protoplanetary disks

Krauß¹,

Wurm²,

Mousis

et al. 2006

A&A

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Context. Protoplanetary disks start their lives with a dust free inner region where the temperatures are higher than the sublimation temperature of solids. As the star illuminates the innermost particles, which are immersed in gas at the sublimation edge, these particles are subject to a photophoretic force. Aims. We examine the motion of dust particles at the inner edge of protoplanetary disks due to photophoretic drag. Methods. We give a detailed treatment of the photophoretic force for particles in protoplanetary disks. The force is applied to particles at the inner edge of a protoplanetary disk and the dynamical behavior of the particles is analyzed. Results. We find that, in a laminar disk, photophoretic drag increases the size of the inner hole after accretion onto the central body has become subdued. This region within the hole becomes an optically transparent zone containing gas and large dusty particles ( 10 cm), but devoid of, or strongly depleted in, smaller dust aggregates. Photophoresis can clear the inner disk of dust out to 10 AU in less than 1 Myr. The details of this clearance depend on the size distribution of the dust. Any replenishment of the dust within the cleared region will be continuously and rapidly swept out to the edge. At late times, the edge reaches a stable equilibrium between inward drift and photophoretic outward drift, at a distance of some tens of AU. Eventually, the edge will move inwards again as the disk disperses, shifting the equilibrium position back from about 40 AU to below 30 AU in 1-2 Myr in the disk model. In a turbulent disk, diffusion can delay the clearing of a disk by photophoresis. Smaller and/or age-independent holes of radii of a few AU are also possible outcomes of turbulent diffusion counteracting photophoresis. Conclusions. This outward and then inward moving edge marks a region of high dust concentration. This density enhancement, and the efficient transport of particles from close to the star to large distances away, can explain features of comets such as high measured ratios of crystalline to amorphous silicates, and has a large number of other applications.

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“…The latter is not known for realistic materials, and its determination requires complicated numerical procedures (see, e.g. Mackowski 1989). Analytical solutions are possible, but only in the cases of high or low absorption coefficients (see Arnold & Lewittes 1982).…”

Section: Radiation Pressurementioning

confidence: 99%

Effects of photophoresis on the evolution of transitional circumstellar disks

Herrmann¹,

Krivov²

2007

A&A

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Although known for almost a century, the photophoretic force has only recently been considered in astrophysical context for the first time. In our work, we have examined the effect of photophoresis, acting together with stellar gravity, radiation pressure, and gas drag, on the evolution of solids in transitional circumstellar disks. We have applied our calculations to four different systems: the disks of HR 4796A and HD 141569A, which are several Myr-old AB-type stars, and two hypothetical systems that correspond to the solar nebula after disk dispersal has progressed sufficiently for the disk to become optically thin. Our results suggest that solid objects migrate inward or outward, until they reach a certain size-dependent stability distance from the star. The larger the bodies, the closer to the star they tend to accumulate. Photophoresis increases the stability radii, moving objects to larger distances. What is more, photophoresis may cause formation of a belt of objects, but only in a certain range of sizes and only around low-luminosity stars. The effects of photophoresis are noticeable in the size range from several micrometers to several centimeters (for older transitional disks) or even several meters (for younger, more gaseous, ones). We argue that due to gas damping, rotation does not substantially inhibit photophoresis.

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Photophoresis of aerosol particles in the free molecular and slip-flow regimes

Cited by 105 publications

References 16 publications

Thermophoresis and Photophoresis of an Aerosol Cylinder with Thermal Stress Slip

Thermophoresis and Photophoresis of an Aerosol Cylinder with Thermal Stress Slip

The photophoretic sweeping of dust in transient protoplanetary disks

Effects of photophoresis on the evolution of transitional circumstellar disks

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