Effect of Joule heating on orientation of spheroidal particle in alternating electric field

2008 ◽  
Vol 104 (2) ◽  
pp. 024903 ◽  
Author(s):  
Yu. Dolinsky ◽  
T. Elperin
2019 ◽  
Vol 9 (3) ◽  
pp. 344-352 ◽  
Author(s):  
L.I. Stefanovich ◽  
O.Y. Mazur ◽  
V.V. Sobolev

Introduction: Within the framework of the phenomenological theory of phase transitions of the second kind of Ginzburg-Landau, the kinetics of ordering of a rapidly quenched highly nonequilibrium domain structure is considered using the lithium tantalate and lithium niobate crystals as an example. Experimental: Using the statistical approach, evolution equations describing the formation of the domain structure under the influence of a high-frequency alternating electric field in the form of a standing wave were obtained. Numerical analysis has shown the possibility of forming thermodynamically stable mono- and polydomain structures. It turned out that the process of relaxation of the system to the state of thermodynamic equilibrium can proceed directly or with the formation of intermediate quasi-stationary polydomain asymmetric phases. Results: It is shown that the formation of Regular Domain Structures (RDS) is of a threshold character and occurs under the influence of an alternating electric field with an amplitude less than the critical value, whose value depends on the field frequency. The conditions for the formation of RDSs with a micrometer spatial scale were determined. Conclusion: As shown by numerical studies, the RDSs obtained retain their stability, i.e. do not disappear even after turning off the external electric field. Qualitative analysis using lithium niobate crystals as an example has shown the possibility of RDSs formation in high-frequency fields with small amplitude under resonance conditions


2001 ◽  
Vol 32 ◽  
pp. 951-952
Author(s):  
M. LACKOWSKI ◽  
A. JAWOREK ◽  
A. KRUPA

Author(s):  
Zhengwei Ge ◽  
Chun Yang

Microfluidic concentration of sample species is achieved using the temperature gradient focusing (TGF) in a microchannel with a step change in the cross-section under a pure direct current (DC) field or a combined alternating current (AC) and DC electric field. Experiments were carried out to study the effects of applied voltage, buffer concentration and channel size on sample concentration in the TGF processes. These effects were analyzed and summarized using a dimensionless Joule number that is introduced in this study. In addition, Joule number effect in the Poly-dimethylsiloxane (PDMS)/PDMS microdevice was compared with the PDMS/Glass microdevice. A more than 450-fold concentration enhancement was obtained within 75 seconds in the PDMS/PDMS microdevice. Results also showed that the high frequency AC electric field which contributes to produce the temperature gradient and reduces the required DC voltage for the sample concentration. The lower DC voltage has generated slower electroosmotic flow (EOF), which reduces the backpressure effect associated with the finite reservoir size. Finally, a more than 2500-fold concentration enhancement was obtained within 14 minutes in the PDMS/PDMS microdevice, which was a great achievement in this TGF technique using inherent Joule heating effects.


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