Review Reports

Round 1

Reviewer 1 Report

The authors have presented an interesting contribution on the modelling of homogeneous/heterogeneous condensation employing the method of moments formalism, and applied it to a couple of test cases. In my opinion, the paper can be a valuable addition to the readers of Fluids, after some minor points are clarified below.

1. The authors concentrate modelling efforts of the condensation process by using a standard method o moments. However, there are other types of moment methods in the literature e.g. employing quadrature type closures, which may often facilitate the source term modelling in the condensation equations, and not rely on unnecessary approximations to formulate a self-closed set of moment transport equations. Could the authors elaborate on the choice of standard moment method over quadrature based methods? In view of this, it would be interesting to add up a few references on other quadrature-based moment methods to tackle to the condensation problem in literature review and a discussion about the advantages and disadvantages of each. A.G. Gerber, A. Mousavi. Representing Polydispersed Droplet Behavior in Nucleating Steam Flow. JFE, 2007
2. The authors present equations for the viscosity and thermal conductivities (Eq.18), including laminar and turbulent contributions. Is any of the test cases analyzed in turbulent flow conditions? If so, what type of turbulence modelling was employed? If not, there is no need to include a turbulent contribution to the diffusivities. This information was nowhere to found.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

A mathematical model for numerical simulation of the flow with homogeneous and heterogeneous phase transitions is provided in the present manuscript. In my opinion, there are two contributions to the model of the multiphase flow. The first one is about the joint occurrence of heterogeneous and homogeneous condensation processes. With the assumption of the independency of the two processes, the moment equations are just directly combined. The second one is about the evaporation which is also considered in the present model. The present framework is helpful to investigate the flow with phase transition.

The present model is validated by two cases, homogeneous condensation in Laval nozzle and heterogeneous condensation in shoch tube, respectively. Not surprisingly, good agreements between the present numerical simulations and the experiments are observed. Then the model is used to simulate the cleaning smoky gas in an ejector device. The discussion about the results, especially for the effect of the evaporation, should be more clearly.

Figure 1 and Figure 2 look the same as Fig. 1 in [26]. It is better to declare or explain clearly.

I don’t understand ‘in two-dimensional plane and axisymmetric regions’ in the abstract. The present model is described only in cylindrical coordinate system.

Equation (18) should be explained clearly. Is it for the Reynolds stress?

Line 345: Figure 4 should be Figure 5.

Author Response

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Author Response File: Author Response.pdf