Research of VDT scheme for porous media thermal-hydraulics analysis of plate-type fuel assembly.

• Proposing and developing a Virtual Domain Technology (VDT) scheme that inherits the computational advantages of porous media models while achieving the spatial resolution of CFD for thermal-hydraulics analysis. • The proposed VDT enables flexible creation and adjustment of virtual domains within porous media through localized resistance without changing the mesh. • VDT shows great computational resolution and accuracy. This study verifies the thermal-hydraulics calculation of two-dimensional Karman vortex street and CARR reactor standard fuel assembly. • Thermal-hydraulics calculation for the standard fuel assembly of CARR reactor, compared with the refined CFD, the grid amount of VDT is reduced by 94%, and the calculation time is reduced by 94.303%. Thermal-hydraulics analysis of nuclear reactor core is crucial for the safe operation of nuclear power plants. Porous media models in computational fluid dynamics (CFD) code are commonly used to simulate flow and heat transfer in nuclear reactor cores because they simplify geometry and reduce computational cost. However, their low spatial resolution limits detailed analysis of internal flow and temperature fields. This research develops a Virtual Domain Technology (VDT) scheme to improve the resolution of porous media models without increasing mesh density. VDT sets localized resistance coefficients to create virtual solid and fluid domains within the porous core representation. The flow and thermal effects of these virtual domains mimic real structural effects. VDT was verified on a cylinder flow case and showed excellent agreement with CFD for velocity and pressure fields. Application to a plate-type research reactor core demonstrated VDT's ability to capture detailed temperature profiles and flow traces consistent with CFD, using only 6% as many mesh cells. By improving spatial resolution, VDT enhances porous media-based modeling of reactor cores to provide more accurate thermal-hydraulics analysis, while maintaining computational efficiency. This will aid optimization and safety analysis for advanced reactor designs. [ABSTRACT FROM AUTHOR]