Numerical analysis of thermal conductivity effect on thermophoresis of a charged colloidal particle in aqueous media

Numerical Analysis of Thermophoresis of a Charged Spheroidal Colloid in Aqueous Media

“…For the extremely thin EDL case (i.e., ), the particle curvature’s effect on the ion distribution is negligible, and the ions move relatively with respect to a planar surface [ 37 ]. Moreover, according to our previous work [ 14 ], the thermophoretic velocity is proportional to the local temperature gradient at the upper pole of the particle surface ( for prolate spheroids and for oblate spheroids). Therefore, the thermophoretic problem for the extremely thin EDL case can be treated as a thermal creep flow around the particle surface, and the thermophoretic force is balanced by the viscous drag [ 38 ].…”

“…As has been discussed in the literature [ 14 ], the temperature distributions are governed by the energy equation as where and are the thermal conductivities of particle and fluid, respectively. is the fluid density and is the fluid heat capacity.…”

“…The flow of the electrolyte solution is governed by the Navier–Stokes equations as where the fluid velocity with and as radial and axial velocities, respectively, and is the fluid pressure. The dynamic viscosity and the fluid permittivity are assumed to be the same as those of water, with the expressions respectively being and [ 14 ]. In Equation (4), the last two terms on the right-hand side are the electric body force and the dielectrophoretic force acting on the fluid, where is the free electric charge density, and is the local electric field.…”

“…Extensive theoretical [ 13 , 14 , 15 ] and experimental studies [ 16 , 17 , 18 ] on thermophoresis of spherical particles in aqueous solutions have investigated various effects of the particle size [ 19 , 20 , 21 ], electrolyte concentrations [ 22 , 23 ] and types [ 24 ], the bulk temperature [ 25 ], and so on. However, as most biological and biocompatible compounds in aqueous solutions are non-spherical [ 8 ], the interest in colloidal thermophoresis of non-spherical particles is considerably increasing.…”

Switching between laser‐induced thermophoresis and thermal convection of liquid suspension in a microgap with variable dimension

“…Temperature gradient in fluids exerts a thermophoretic force on dispersed micro-/nanoparticles [1,2] and biomolecules [3]. Since the direction of thermophoretic forces is controllable by choosing appropriate experimental conditions, such as background temperature [4,5], salt concentration [6][7][8][9], additional polymer concentration [10], the surface/bulk characteristics of target particles [11][12][13], and/or the length of biomolecules [14,15], the use of thermophoretic forces is expected to develop novel separation technique of the mixture of tiny objects. A key to realize such techniques is the method of producing a strong temperature gradient in sample solutions.…”