ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Motion control of silica nanoparticles in nanofluid at high-harmonics

Richard Nii Ayitey Akoto, Harrison Osei, Eric Neebo Wiah, and Samuel Ntim

School of Graduate Studies, University of Professional Studies, Accra, Ghana

E-mail: hosei@umat.edu.gh

Received: 24 December 2025  Accepted: 4 April 2026

Abstract:

Harmonic electric field mixing is established as a computationally demonstrated strategy for controlling nanoparticle transport and enhancing thermal conductivity in aqueous nanofluids. Silica nanoparticle dynamics are investigated in water under two harmonically coupled AC electric fields, where the secondary frequency is set to exactly double the primary frequency without DC bias. Through integrated analytical modeling incorporating both linear response and nonlinear field-dependent charge effects, it is demonstrated that odd-harmonic fields produce a 62 ± 8% greater nanoparticle velocity response than even harmonics via nonlinear frequency mixing enhanced by inertial selectivity. Parametric analysis reveals nanoparticle radius and surface charge as critical control parameters: size reduction from 40 to 20  Å  is shown to enhance mobility by 230 % due to favorable electrophoretic force-to-drag scaling. Direct MD computations employing the Green-Kubo method confirm that odd-harmonic excitation generates high-frequency microconvection, achieving up to 30.8 % thermal conductivity enhancement—approximately 3\(\times \) greater than even harmonics. Beyond Brownian motion, nanoparticle size, field amplitudes and frequencies, and surface charge are identified as the primary parameters governing motion control. The validated framework demonstrates precise harmonic selectivity, offering a pathway toward frequency-selective nanoscale transport control, with potential implications for electrodeposition, adaptive thermal interfaces, and the development of smart coatings and coolants with controllable thermal properties. While demonstrated here using high field strengths for computational expediency, the identified scaling laws provide quantitative design criteria for translating this selective control to experimentally accessible conditions.

Keywords: Brownian motion; Electric field; Molecular dynamics; Nanofluid; Silica

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04885-4

Chemical Papers 80 (7) 8249–8265 (2026)