Near-field radiative transfer between two unequal sized spheres with large size disparities

Area of Science:

• Thermodynamics
• Near-field radiative heat transfer
• Nanoscale energy transport

Background:

• Near-field radiative transfer (NFRT) is crucial for nanoscale energy transport.
• Accurate computation of NFRT between objects with unequal radii and small gaps is challenging.
• Existing methods require modifications for specific geometries and gap sizes.

Purpose of the Study:

• To compute near-field radiative transfer between two spheres with unequal radii (R2 ≲ 40R1).
• To develop and validate modified computational methods for NFRT in small gaps (d ≪ R1).
• To compare computed results with the modified proximity approximation.

Main Methods:

• Approximation of vector translation theorem coefficients for the d ≪ R1 limit.
• Derivation of recursion relations for normalized translation coefficients.
• Replacement of spherical Bessel and Hankel function computations with their ratios.

Main Results:

• Successful computation of near-field radiative transfer for R2 = 40R1 down to a gap of d = 0.016R1.
• Demonstration of a modified computational approach for NFRT between unequal spheres.
• Comparison of results with the modified proximity approximation.

Conclusions:

• The modified computational methods enable accurate NFRT calculations for unequal spheres at small gaps.
• The study provides a validated approach for investigating NFRT in challenging nanoscale geometries.
• Findings contribute to understanding and predicting radiative heat transfer at the nanoscale.