## 2 Methodology  
### Geometry Generation  
The primary difficulty in preparing the computational domain examined for CFD calculations lies in accurately constructing the channels defined by the complex surface of the HP and the brazed areas.  
While the central region of the channel, as shown in Figure 2, is composed of interconnected base unit volumes--highlighted in red in Figure 2c--and could be approximated by distributing a double cosine wave across space, predicting the outer zones near the ports remains challenging due to the variations in dimple shape and size. Indeed, they not only differ from those in the middle part but also vary across geometries to meet certain application requirements.  
For a realistic representation of the corrugated component, the HP surface has been obtained implementing forming simulations in the commercial tool Ansys Forming 23 R1, employing the theory of explicit dynamics [22] when handling large deformations and strains, along with complex contacts. The process involves a time-discretized analysis, where the sheet metal plate, made of steel grade AISI 316L, is treated as a surface with zero physical thickness, which was assigned mathematically. The material behavior was specified by modeling the yield surface based on the work of [PERSON] et al. [23], with the flow stress derived from the combination of uniaxial tension and bulge tests. The input objects were the CAD models of the pressing dies, including the waffles and the forming ring. The procedure was validated by comparing the resulting HPs with 3D scanning measurements of plates that were actually produced. Three distinct geometries, differing in overall size and dimple features, were generated based on a series of tests conducted on their corresponding channels, as detailed in the following sections. An example of the simulated HPs is presented in Figure 3a.  
In examining the repetitive pattern, the primary parameters defining the heat plate, as indicated in Figure 2b, are the profile height \(h\), which determines the channel height, and the longitudinal and transverse pitch, denoted by \(p\) (equal in these cases). The overall dimensions, as shown in Figure 3b, are specified by the width \(W\), length \(L\), the diameter \(D_{p}\) of the ports, and their distance \(L_{p}\). The values for the three HPs, scaled relative to those of the third one, are summarized in Table 1.  
Figure 2: Details of the central region of (**a**) a two-plate assembly with dimpled corrugation; (**b**) cross-sectional view illustrating the characteristic geometrical parameters; (**c**) corresponding flow channel.  
The computational domain was generated by first converting the STL file from the forming simulation into a CAD model using surface patches, thereby replicating the initially imported HP. This approach was adopted as it offers the advantage of enabling conformal meshes, which are beneficial for future conjugate heat transfer (CHT) simulations. The comparison between the converted and original HP models has shown a maximum deviation of 1.5% of the \(h\).  
Conversely, due to the method used to construct the domain, the size of the derived CAD file and the corresponding grid are not compatible with modeling an entire PHE, which typically consists of dozens to hundreds of plates.