# Comment on Cimmelli, V.A. Interpretation of Second Law of Thermodynamics in Extended Procedures for the Exploitation of the Entropy Inequality: Korteweg Fluids and Strain-Gradient Elasticity as Examples. Entropy 2024, 26, 293

## TL;DR

This paper comments on a recent study about thermodynamics and fluid mechanics, pointing out inaccuracies in the claims made.

## Contribution

The paper corrects a misinterpretation regarding the compatibility of Korteweg fluids with the second law of thermodynamics.

## Key findings

- The constitutive equation of Korteweg fluids is not incompatible with the second law of thermodynamics.
- The claims that all solutions modify the energy balance or entropy flux are not entirely accurate.

## Abstract

In a recent paper (Entropy 2024, 26, 293), Cimmelli makes use of the constitutive equation of Korteweg fluids to justify the introduction of an extended method to the classical Coleman–Noll procedure. He states that this constitutive equation is incompatible with the second law of thermodynamics and that while several different proposals can be found in the literature to circumvent such a problem, all of them modify the energy balance or entropy flux. Here we note that such statements are not completely true.