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Zotin K.-H. Chu
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We make some remarks on Sokhan and Quirkes [{it Phys. Rev. E} 78, 015301(R) (2008)] paper (arXiv:0805.1666). Sokhan and Quirke mentioned that, considering their main result, {the slip coefficient is independent of the external force (flux)} which is not consistent with previous measurements and approaches. We also discuss the sudden changes of the slip coefficient for larger Knudsen numbers or smaller nanopores.
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We make remarks on Sofos {it et al.}s [{it Phys. Rev. E} 79, 026305 (2009)] paper. The focus is about the monotonicity of the slip length of which it is different from previous similar numerical simulation. We also offer a possible explanation for this.
We make remarks on Neufeld {it et al.}s [{it Phys. Rev. C} 78, 041901(R) (2008), arXiv:0802.2254] paper especially about the Mach cone formation. We argue that the original bow shock structure (as a fast parton moving through a quark-gluon plasma) has been smeared out after the approximations made by Neufeld {it et al.}
In a series of papers, Bartelt and co-workers developed novel snow-avalanche models in which emph{random kinetic energy} $R_K$ (a.k.a. granular temperature) is a key concept. The earliest models were for a single, constant density layer, using a Voellmy model but with $R_K$-dependent friction parameters. This was then extended to variable density, and finally a suspension layer (powder-snow cloud) was added. The physical basis and mathematical formulation of these models is critically reviewed here, with the following main findings: (i) Key assumptions in the original RKE model differ substantially from established results on dense granular flows; in particular, the effective friction coefficient decreases to zero with velocity in the RKE model. (ii) In the variable-density model, non-canonical interpretation of the energy balance leads to a third-order evolution equation for the flow depth or density, whereas the stated assumptions imply a first-order equation. (iii) The model for the suspension layer neglects gravity and disregards well established theoretical and experimental results on particulate gravity currents. Some options for improving these aspects are discussed.
We derive general conditions of slip of a fluid on the boundary. Under these conditions the velocity of the fluid on the immovable boundary is a function of the normal and tangential components of the force acting on the surface of the fluid. A problem on stationary flow of an electrorheological fluid in which the terms of slip are specified on one part of the boundary and surface forces are given on the other is formulated and studied. Existence of a solution of this problem is proved by using the methods of penalty functions, monotonicity and compactness. It is shown that the method of penalty functions and the Galerkin approximations can be used for the approximate solution of the problem under consideration.
This article focuses on correcting several factual errors and critiques in the previously published Letter in Phys. Rev. L, Vol. 89, No. 10, 2022, by D. Shapira and M. Saltmarsh. The authors of the Letter did not perform their own independent experiments as claimed; they did not perform control experiments with normal acetone; and, neither did they monitor for tritium. It their Letter, the authors (D. Shapira and M. Saltmarsh) failed to disclose that the data they collected actually confirmed our claims of having observed statistically significant nuclear emissions in chilled, cavitated deuterated acetone.
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