The Numerical Analysis of Non-Newtonian Blood Flow in a Mechanical Heart Valve
Round 1
Reviewer 1 Report
The manuscript investigates the impact of the non-Newtonian nature of the blood fluid on the numerical simulation of the velocity field in a mechanical heart valve by using an open-source code, OpenFoam. In this regard, a thorough analysis of different constitutive models reported in the literature is conducted, and the results are compared. Eventually, the authors conclude that the Newtonian model may result in a strong assumption for capturing the detail at some stages of the process.
The work is well-motivated, and the results are clearly reported.
It surprised me that the authors did not also consider the Herschel-Bulkley model, one of the most commonly used models for the description of non-Newtonian fluids. The authors should at least explain the rationale for this exclusion, which looks strange to me because the HB model has also been applied to blood rheology.
The article is, in general, well-written. However, there are some parts of the work whose English is quite sloppy, for example, in rows 225-229 and rows 314-316.
Minor aspects:
Abstract: the word “However” is reported more times
Row 77: “theologies” is written instead of rheology
Row 107: check the spaces between the words
Page 11: The term “Carson” is used instead of “Casson”
Figure 15: remove the title from the figure
Author Response
It surprised me that the authors did not also consider the Herschel-Bulkley model, one of the most commonly used models for the description of non-Newtonian fluids. The authors should at least explain the rationale for this exclusion, which looks strange to me because the HB model has also been applied to blood rheology.
Replay:
A fluid described by a three-parameter rheological model. A Herschel–Bulkley (HB) fluid can be described mathematically as follows:
Where is shear stress, is the yield stress, k is consistency factor, is shear rate, and n is flow index, a power law exponent.
The HB model is sometimes referred to as modified power law or yield power law. Combines the effect of Bingham and the power-law behavior in the fluid. For low strain rates the rigid material acts like a very viscous fluid with viscosity .
In this paper, we report a Modified power-law model: . Which limited the range by and . Which is similar (or same) to the HB model, so that in this paper did not consider the HB model
Reference
- Hemphill T, Campos W, and Pilehvari A: "Yield-Power Law Model More Accurately Predicts Mud Rheology," Oil & Gas Journal 91, no. 34 (August 23, 1993): 45–50.
Reviewer 2 Report
The authors presented a numerical study on the non-Newtonian blood flow in Mechanical Heart Valve.
The introduction is shot and is to be extended.
The novelty of the paper is to be presented at the end of the introduction.
What do you mean by ‘’ non-Newtonian importance factor’’?
Why WSS is chosen as sensitive variable ?
A validation/verification of the numerical model is to be performed.
Why the fluid-structure interaction is not considered.
It will be interesting to present the streamlines for a better understanding of the flow structure.
Some figures have low resolutions?
Check the positions of Eq.1 and the title of Fig 4.(lines 121 and 122 )
The authors solved time dependent equations, without presenting any temporal variation.
What is the considered time step?
The scientific soundness of the paper is to be improved.
It is mandatory to add physical interpretations
The titles of the figs are to be more precise; for example, to which model corresponds Figs 11 to 13?
The English level is to be improved.
A nomenclature is to be added.
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 3 Report
In this study, non-Newtonian effects on the hemodynamic behaviour of mechanical heart valves are investigated in depth. Several constitutive equations proposed to examine the blood rheology are used to analyse the chamber flow and blood viscosity. A comparative study between Newtonian and different non-Newtonian models is also performed. OpenFOAM is used to carry out numerical simulations to analyse its hemodynamic parameters.
This paper is competent and of sufficient interest to warrant publication. Hence my recommendation is that this paper is accepted. As always, the authors are suggested to read the paper for any typos or grammatical errors they may find before final acceptance.
Author Response
The paper has been proofread, thanks for the review
Round 2
Reviewer 2 Report
Accept as it
