The Stability of Natural Convection in an Inclined Fluid Layer in the Presence of AC Electric Field

Printing orderly patterns on the insulating collector is the key for the development and application of flexible electronics. However, electrospinning on the insulating collector still has the problem of unstable jet due to the charge accumulation. The alternating current (AC)-induced electrohydrodynamic direct-writing (EDW) technology is a good way to decrease the interferences of charge repulsion, which is beneficial to printing orderly micro/nanostructures on the insulating collector. In this work, the sinusoidal AC-induced EDW is used to enhance the stability of charged jet and the deposition behaviors under AC electric field are also studied. The reciprocation transferring of charges induced by the AC electric field decreased the density of the accumulating charges on the insulating collector. The effect of AC electric field parameters on the direct-written micro/nanostructures are investigated to optimize the printing process. As the voltage peak increases, the fiber deposition bandwidth shows a trend of decreasing first and then increasing. Increasing the voltage frequency appropriately is beneficial to decrease the bandwidth of fiber deposition and to increase the stability of the jet. By improving the stability and controllability of the jet printing process, precise micro/nanopatterns can be direct-written on the insulating collector. This research provides a good foundation for expanding the application fields of EDW.

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Natural Convection in Horizontal Thin-Walled Honeycomb Panels

Journal of Heat Transfer ◽

10.1115/1.3450086 ◽

1973 ◽

Vol 95 (4) ◽

pp. 439-444 ◽

Cited By ~ 33

Author(s):

K. G. T. Hollands

Keyword(s):

Heat Transfer ◽

Natural Convection ◽

Fluid Layer ◽

Convection Heat Transfer ◽

Correlation Equation ◽

Wave Number ◽

Equivalent Wave ◽

Side Walls ◽

The Stability ◽

Rayleigh Numbers

This paper presents an experimental study of the stability of and natural convection heat transfer through a horizontal fluid layer heated from below and constrained internally by a honeycomb. Examination of the types of boundary conditions exacted on the fluid at the cell side-walls has shown that there are three limiting cases: (1) perfectly conducting side-walls; (2) perfectly adiabatic side-walls; and (3) side-walls having zero thickness. Experiments described in this paper approach the latter category. The fluid used is air and the honeycomb used is square-celled. Measured critical Rayleigh numbers are found to be intermediate between those applying to cases (1) and (2), and consistent with an “equivalent wave number” of approximately 0.95 times that for case (1). The measured natural convective heat transfer after instability is found to be significantly less than that predicted by the Malkus-Veronis power integral technique. However, it is found to approach asymptotically the heat transfer which would take place through a similar fluid layer unconstrained by a honeycomb. A general correlation equation for the heat transfer is given.

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Stability of transient natural convection in impulsively heated inclined fluid layer

Fluid Dynamics Research ◽

10.1088/1873-7005/abad8b ◽

2020 ◽

Vol 52 (5) ◽

pp. 055501

Author(s):

Manisha Arora ◽

Renu Bajaj

Keyword(s):

Natural Convection ◽

Fluid Layer ◽

Transient Natural Convection ◽

Inclined Fluid Layer

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