The manuscript discusses the use of a digital twin to perform wind turbine and airfoil tests in wind tunnels with turbulent inflows. Hot-wire anemometry is first used to characterize grid-generated turbulence in the wind tunnel. Pressure and force sensors are then applied  to record the pressure, drag and lift coefficients of an airfoil under different angles of attack at a chord-based Reynolds number of 2.0x10^5. On the other hand, RANS simulations at the same Reynolds number are used to capture the kinetic energy decay of the grid-generated flows and the different coefficients within the airfoil. Good agreement is found between all quantities, provided that the Taylor microscale is used in the RANS simulations as the length scale required to simulate the grid-generated turbulent flow.

I find the thematic of this manuscript within the scope of the journal. Furthermore, it is well written and organized, with a theoretical discussion and numerical results that are of interest for the wind energy community. Nevertheless, before recommending publication the authors should assess the following points:

- Several arguments used to deduce equations 23 and 27 rely on the presence of a fully developed grid-generated turbulent flow, that is only found far downstream the grid. The range studied here (x<30M, with the airfoil placed at x~20M) may present some differences in terms of the approximations made in equations 10, 13 and 20. While the authors refer to a previous publication from the group, these points should be addressed in the present manuscript.

- Related to my previous point, several papers discuss the decay of kinetic energy in terms of invariants (Sinhuber et al, PRL 2015; Krogstad and Davidson JFM 2009), and also the role of the integral length scale on such models. Furthermore, the power laws predicted contain a virtual origin that is not present in the theoretical discussion of the present work. First, these approaches should be mentioned at the section ‘Brief theoretical description of decaying grid turbulence’. Second, they should be at least addressed when figure 4 is presented. Have the authors tried to compare their data with them? Are the decay exponents near the ones predicted in such papers?

- Presenting figure 4 in logarithmic scale (or using an inset for that) would help to assess the quality of the power-law adjustment. Also, if I understand correctly, the theoretical curve has no fitting parameters? If that is the case, it should be made more explicit on the text as it is a relevant result.

- To properly address the relevance of the Taylor scale on the RANS models, a more systematic study with several grids (producing different values of integral and Taylor scales) should be performed. The present study is an interesting contribution pointing towards the relevance of the Taylor scale in RANS modelling, but gives no conclusive proof. I consider that the conclusions should emphasize this point.

- The accuracy of the numerical simulation in the estimation of different coefficients is discussed in terms of the experimental results but not compared with other numerical works/schemes. I suggest that the authors discuss other works from the literature when presenting figures 16 to 22. Also, those figures should have error bars added.

- I also suggest that figures 11 to 15 are merged onto a single one.

General comments:

 This manuscript is an interesting study on grid generated turbulence, its modelling, and its effect on aerodynamic forces in the flow around an airfoil. The topic is investigated using a combination of theoretical, computational, and experimental approaches, and the results and conclusions are of interest of the readership of Wind Energy Science and the fluid mechanics community in general. The recommendation of using the Taylor micro-scale to define RANS inlet boundary conditions is very useful for high-fidelity modelling in wind energy.

So, the work constitutes a contribution that deserves to be published, but there are many corrections and improvements that need to be made before. They are listed below.

Specific comments:

1. Page 2, line 25: The manuscript says “Alternatively, experiments can be conducted in a wind tunnel by subjecting a Reynolds-scaled wind turbine rotor or a blade section from a real wind turbine blade to turbulent inflow under different inflow conditions, such as homogeneous inflow or gust inflow.” Wind turbine rotor models for wind tunnel tests are usually not scaled according to the Reynolds number, because in this case the wind speed in the tunnel would have to be prohibitively high. They usually obey Strouhal similarity (i.e., keep the same tip speed ratio). Some sort of measure has to be taken or assumption has to be made to account for this Reynolds number discrepancy. Roughness elements can be added to the blades, or it the experiments can be run in a way that it guarantees that the flow will be fully turbulent at the rotor blades boundary layer (wind speed or turbulent kinetic energy high enough). For rotor blade sections tested in fixed conditions, as the case of the tests reported in this manuscript, the situation is different. So, I believe this sentence should be rewritten.
2. Page 2, line 52: The manuscript says “The Navier-Stokes equations are highly nonlinear…”. The Navier-Stokes equations have just one nonlinear term, and it is a quadratic term. In my point of view, this does not make them “highly” nonlinear. I suggest the authors remove the term “highly”.
3. Page 2, line 53: Why do the authors use GDT as acronym for grid-generated turbulence? Would not be more appropriate to use GGT?
4. Page 3, line 58: The authors should mathematically define TKE and dissipation at this point.
5. Page 5, section 2.1: I believe the manuscript would benefit from an explanation of the physical meaning/definition of the Taylor micro-scale at this point. The authors should also mention how it could be calculated or measured.
6. Pages 10-11, section 3.2: The authors should present the equations that are solved in the RANS simulations, and the values of the constants that were employed in the turbulence quantities transport equations.
7. Pages 12-13, section 3.4: The authors must run the same validation test for other wind speeds and add the results to this section.
8. Pages 17-19, section 4.2: The mathematical expressions of the boundary conditions must be presented (for velocity, pressure, and turbulence quantities). What was the initial condition used for the flow simulations? What were the wall functions employed at the top, bottom, and side walls? What were the value of y+ on those walls?
9. Page 21, line 400: The manuscript says “However, there is a slight tendency towards higher pressure on the pressure side, which could be attributed to difficulties in defining the reference pressure (which was measured inside the blade).”. What data shows this tendency? I guess it is the experimental set, but this should be stated clearly in the text. If the reason is difficulties in defining the reference pressure, why does not that affect the other measurement points?
10. Page 21, line 404: The sentence “Nevertheless, these differences are not significant for these local quantities.” is unclear. What are the authors trying to say?
11. Page 23, Figure 20: I believe the caption of the figure is wrong, because that graph probably refer to an angle of attack other than 0°, since results for that AoA are already shown in Figure 18.
12. Page 23, line 414: “The discrepancy in Cl values between the 3d and 2d digital twins can be traced back to the escalating significance of 3d effects at and above 14° AoAs, which are unaccounted for in the 2d model.” What 3d effects are those? It is necessary to provide a clear physical explanation here.

Technical corrections:

1. Page 2, line 30: Change “Veers et al. (2019)” to “(Veers et al., 2019)”. The same correction applies to line 90.
2. Page 2, line 31: Change “millions” to “million”.
3. Page 2, line 34: Change “a key” to “key” (in this sentence, key is an adjective, not a noun).
4. Page 3, line 57: Change “(Kurian and Fransson (2009))” to “(Kurian and Fransson, 2009)”. This type of mistake happens in many other places of the manuscript (lines 27-28, 73, 74, 75, 91 …), please perform a thorough check.
5. Page 3, line 62: Change “computational fluid mechanics” to “computational fluid dynamics”.
6. Page 3, line 79: Delete “have”.
7. Page 4, line 97: Change “a perfect” to “an adequate”.
8. Page 5, line 136: Delete “on”.
9. Page 5, line 145: Change “This is confirmed” to “This was confirmed”.
10. Page 8, line 210: Remove paragraph indentation.
11. Page 11, line 273: Change “the ones” to “those”.
12. Page 13, figure 4: Add “(23)” after “Equation” in the figure legend.
13. Page 17, line 353: Change “airfoil’s cross section” to “model planform area”.