## 3 Results  
### Silver Specim  
The transient oscillations in heat transfer coefficient due to complex bubble motion are shown in Figure 6. This plot, however, without a lumped model and the outlined time instances, has been shown in [38]. Hence, in this paper, new insights on the obtained results with the proposed numerical method are made, accompanied by the lumped heat conduction estimate. At \(t=0\) s, the specimen is immersed in the cooling water and has been kept through the simulation at the place. The initial simulation time has been shifted for a time increment due to the presence of an initial vapor layer. The dashed line shows the distribution of the heat transfer coefficient at the outer surface of the cylinder specimen derived by the simulation. The transient oscillations in the heat transfer coefficient could be explained by  
Figure 5: Thermal diffusivity of Inconel 600 with respect to the material temperature. Figure 6: Comparison of the heat transfer coefficient calculated using different approaches. The vertical long dash lines denote the time instances with observable bubble detachments (maximum heat transfer coefficient values) and continuous vapor, i.e., dry zones. the intermittent occurrence of dry spots, i.e., the areas where the heat transfer surface is not being wetted by the surrounding liquid, and hence, the heat transfer is less active. The red solid line indicates the time-averaged simulation result, yielding a conclusion that slightly overestimates the error band associated with the correlation data used in the investigation. For plausibility, we added the heat transfer coefficient (green dash dotted line) derived with the lumped heat conduction model for the simulated temperature in the center of the specimen at \(t=0\) and \(t=15\) s.  
As shown in [PERSON] [1], the bubble detachment and dry areas are causing local maximums and minimums in the heat flux distribution, respectively; the tendency is evident within the present research, as shown in Figure 6. In this case, the global minimum is reported at \(t=3.0\) and reads \(h=171\) W/(m\({}^{2}\) K), whilst the global maximum is noted at the time instance \(t=13.0\) s with \(h=292\) W/(m\({}^{2}\) K). Both extrema with their neighborhood counterparts were denoted in Figure 6 and further examined herein. The vapor bubble is generated after enough heat is transferred to a layer in the vicinity of the heated surface. The bubble formation and its interaction with the surroundings is described in [PERSON] [48]. The bubbles are generated at the so-called nucleation sites, whose number also depends on the heat flux at the heated surface. Once generated, the bubble receives the heat input from the bulk liquid since the liquid is in a meta-stable superheated state and evaporates at the interface between the vapor and liquid. Thus, the vapor bubble grows and, at a certain time instance, detaches from the nucleation site with the frequency of detachment that depends on the heat load imposed at the bottom surface. After the disbalance in forces acting on the bubble, according to the theoretical exposure in [PERSON] et al. [49], the bubble departs, the vapor bubble rises, liquid flows afterwards to re-fill the vapor volume, and finally, the vapor bubble reaches the free surface of the liquid and causes the instability of the free surface of the liquid. Referring to the left part of the heat transfer coefficient distribution (dashed red line), the peak in the heat transfer coefficient coincides with the detached bubble at the top horizontal surface of a specimen, as shown in Figure 7a. Also, the minimum value (local minimum) is found at a point where continuous vapor film is present from the horizontal surface of the specimen to the free surface level, as shown in Figure 7b. Figure 7: (**a**) Bubble detachment; (**b**) a continuous vapor zone between the free surface of the liquid and the top horizontal surface of the specimen. The selected time instances are \(t=2.62\) s and \(t=3.02\) s. Blue is liquid; red is the vapor zone.