Analytical approximation to the complex refractive index of nanofluids with extended applicability

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Existing analytical approximations for nanofluid effective refractive index, such as Maxwell Garnett and Foldy-Lax, have limitations.
• These models are typically valid only for very small nanoparticles or highly dilute nanofluids (below 1% volume fraction).
• A need exists for a more comprehensive approximation covering the broader domain of nanofluids.

Purpose of the Study:

• To develop a new, simple analytical approximation for the complex effective refractive index of nanofluids.
• To extend the predictive capabilities of existing models to cover higher concentrations and larger nanoparticle sizes.
• To provide physically sound predictions for nanofluids where current approximations fail.

Main Methods:

• Proposed a novel analytical approximation based on local field corrections applied to the Foldy-Lax approximation.
• Developed a new mixing formula for calculating the effective refractive index of nanofluids.
• Compared the predictions of the new formula and existing approximations with experimental data for polystyrene-in-water nanofluids.

Main Results:

• The new mixing formula accurately reproduces the results of established approximations within their known validity domains.
• The proposed approximation provides physically sound predictions for nanofluids beyond the limitations of previous models.
• Experimental validation confirmed the improved accuracy of the new model for polystyrene-in-water nanofluids.

Conclusions:

• The developed analytical approximation offers a more robust and accurate method for determining the effective refractive index of nanofluids.
• This new model expands the applicability of analytical approximations to a wider range of nanofluid compositions.
• The findings contribute to a better understanding and prediction of optical properties in nanofluids.