Computational Fluid Dynamics-Based Systems Engineering for Ground-Based Astronomy

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Please see the attacthed pdf

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Author Response

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Author Response File: Author Response.doc

Reviewer 2 Report

Comments and Suggestions for Authors

Dear editor and authors,

I read the manuscript entitled ``CFD-based Systems Engineering for Ground-based Astronomy'' by Vogiatzis et al. with great interest, specifically as a frequent user of telescopes at both observing sites described in the paper. The paper is definitely worth publishing in the special issue of ``Computation'' but I would recommend a minor revision prior to publication. I would also recommend the authors to submit a preprint to arXiv perhaps in the astro-ph.IM category to attract the astronomical audience to this work -- in this light I would recommend to expand "CFD" in the title (it is expanded in Page 5, which is its 5th appearance in the manuscript).

The abstract does not look very informative to me. I would recommend adding more specific information starting from the observatories being discussed in the paper (TMT/GMT) and going further to the details about the model, its applicability, e.g. to predict the telescope performance etc.

Having read the paper, as an astronomer I am wondering how important is the expected contribution of what is called `dome' seeing to the overall seeing quality? Can the presented modeling approach provide an answer to this question?

A question I would the authors to address is the thermal emission from the instrumentation. While the telescope structure is discussed in great details in the manuscript, nothing is said about instrumentation. However, it is known that the instruments can be significant sources of heat, gas flows (e.g. venting of liquid nitrogen) inside the dome. I understand that the instrumentation for ELTs is still under discussion, however, at least for the GMT, I believe, a lot of information is available for the planned first-light instruments (G-CLEF and GMACS) as well as for the mirror phasing system.

I have another very practical question, which can have a great impact on current observatory operations related to the discussed model: Can it be used in real-time during observatory operations or does it require very heavy calculations which can only be done offline? The availability of a real-time model can give the observer / telescope operator some ideas on, e.g. which parts of the sky would provide the best seeing conditions / LGAO performance providing the real-time metrology, e.g. temperature sensors on the telescope, mirror, and enclosure, wind direction and speed, atmospheric profile from DIMM, and so on. I think that adding a brief discussion about that in the manuscript would benefit the readers looking for `practical' use-cases -- both TMT and GMT are expected to operate in the queue mode, which gives a lot of flexibility of selecting targets in a specific region of the sky. I am not referring here to the feasibility of precise predictions of the atmospheric seeing quality (there is a brief discussion about it in Section 11) but more of a differential behavior of seeing quality across the sky.

One specific question I am wondering about is how the air exhaust from the active mirror cooling system is modeled and is it modeled at all?


Minor comments:

-- page 8, Section 4 heading should start with a capital

-- page 9, Section 7 heading should start with a capital

-- page 9, Section 7.1: please add countries when listing the sites where applicable (USA, Mexico, Spain)

-- page 11, Section 8, again, capitalization in the heading

-- page 15, Figure 7 -- please correct the X axis title

-- page 17, Section 9 heading should start with a capital

-- page 24, Section 10 heading should start with a capital + CFD should be all caps. I would also add TIO in the section heading because the entire Section 10 is about the TMT

-- page 32, Section 12 heading should start with a capital

Author Response

Please see the attachment.

Author Response File: Author Response.doc

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript presents a summary of the aerothemal modeling on ground-based astronomy. This review introduces various aerothermal simulation techniques, and highlights the role of computational fluid dynamics and conjugate heat transfer modeling in ELT system engineering. These simulations and models can greatly help the ELT system design and optimize the performance. Additionally, this review also discusses the potential directions and challenges.  

Author Response

Thank you for your review.