## 6 Conclusions
The here-proposed method for fluid flow assessment can thus be extended to other flat-plate layouts, having walls made entirely of metallic material to give interesting pieces of data for both the augmentation of the literature dataset in terms of fluid oscillation frequencies, and the improvement of existing numerical and theoretical models. To provide a comprehensive summarization of all the results collected in both parts of the experimental work ([29] and present investigation), the main evaluated quantities are listed in Tables 8 and 9 for the vertical bottom heated mode and the horizontal orientation, respectively. Here, \(R_{eq}\) is theevaluated equivalent thermal resistance of the device, _cvt_ and _cvs_ are the coefficients of variation of the wall-to-fluid heat flux over time and along space, respectively, and \(q_{80}\) is the 80 th percentile of the heat flux. Conceptualization, L.P., L.C. and F.B. ; Methodology, L.P., L.C. and F.B. ; Software, L.P.; Validation, L.P., M.S. and C.R. ; Formal analysis, L.P. and C.R. ; Investigation, M.S. and C.R. ; Resources, F.B. ; Data curation, L.P. and L.C. ; Writing--original draft, L.P.; Writing--review & editing, L.C., V.A., M.S. and F.B. ; Visualization, M.S. ; Supervision, L.C., V.A. and F.B. ; Project administration, V.A. and F.B. ; Funding acquisition, V.A. and F.B. All authors have read and agreed to the published version of the manuscript. This research was funded by the European Space Agency (ESA) grant number 4000128640/19/NL/PG/pt, ESA MAP project TOPDESS. Not applicable. The data presented in this study are available on request from the corresponding authors. The data are not publicly available due to the large dataset. The work has been carried out through a fruitful and effective collaboration between the University of Parma and PPRIME Institute--ENSMA (Poitiers). The authors would like to acknowledge the European Space Agency (ESA)'s support. The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & & & & & & \\ \hline  & _Units_ & _50_ & _70_ & _90_ & _120_ & _150_ & _200_ & _250_ \\ \hline \(R_{eq}\) & [K/W] & 0.3 & 0.2 & 0.12 & 0.11 & 0.09 & 0.18 & 0.17 \\ _cvt\({}_{av}\)_ & [\%] & 49.0 & 60.5 & 74.7 & 72.0 & 72.0 & 72.0 & 72.0 \\ _cvt\({}_{std}\)_ & [\%] & 17.0 & 14.6 & 1.13 & 1.37 & 19.5 & 5.6 & 7.5 \\ _cvs\({}_{aw}\)_ & [\%] & 57.0 & 47.7 & 44.7 & 44.0 & 49.6 & 48.2 & 44.6 \\ _cvs\({}_{std}\)_ & [\%] & 19.5 & 17.8 & 10.7 & 13.2 & 10.6 & 9.6 & 8.6 \\ _q80_ & [W/m\({}^{2}\)] & 1068 & 1117 & 415.0 & 33.6 & 13.64 & 14.85 & 20.38 \\ _f4,av_ & [Hz] & - & - & 10.88 & 0.78 & 10.89 & 10.99 & 10.11 \\ _f4,std_ & [Hz] & - & - & 10.88 & 10.84 & 10.22 & 10.38 & 10.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Evaluated quantities for the vertical bottom heated mode orientation. Green and red colors refer to the intermittent flow and the full activation regime, respectively. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & & & & & \\ \hline  & _Units_ & _50_ & _100_ & _150_ & _200_ & _250_ \\ \hline \(R_{eq}\) & [K/W] & 0.48 & 0.10 & 0.10 & 0.11 & 0.11 \\ _cvt\({}_{av}\)_ & [\%] & 70.7 & 74.4 & 60.7 & 60.4 & 60.0 \\ _cvt\({}_{std}\)_ & [\%] & 25.9 & 11.0 & 6.4 & 5.2 & 1.0 \\ _cvs\({}_{aw}\)_ & [\%] & 70.03 & 50.2 & 18.6 & 48.4 & 50.4 \\ _cvs\({}_{std}\)_ & [\%] & 18.23 & 10.5 & 4.1 & 7.0 & 5.8 \\ _q80_ & [W/m\({}^{2}\)] & 1086 & 1045 & 4.84 & 50.2 & 72.0 \\ _f4,av_ & [Hz] & - & 10.84 & 1 & 10.6 & 1.02 \\ _f4,std_ & [Hz] & - & 10.88 & 0.88 & 10.88 & 10.88 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Evaluated quantities for the horizontal orientation. Green and red colors refer to the intermittent flow and the full activation regime, respectively.