Implementation and validation of 1D-3D CFD co-simulation for complete cooling system
Typ
Examensarbete för masterexamen
Program
Applied mechanics (MPAME), MSc
Publicerad
2020
Författare
Konstantinidis, Konstantinos
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
This thesis deals with the development and verification of a method that introduces coupling between one- and
three- dimensional (1D and 3D) numerical simulations of a complete cooling system of a passenger car, as well
as with the advantages of using such a platform. Such method is different from the common practise in the car
industry, in which simplified models are typically used and they consider each component of the system as 1D.
These models are typically based on emperical correlations. However, the 3D models solve for the differential
equations that govern the fluid dynamics of a single-phase coolant and offer more detail in the analysis of a
system. They are used for a part of the cooling system that the 1D models fail to capture the behaviour of the
fluid and the physics. The rest of the cooling circuit will stay 1D, creating a need to device a method to couple
1D and 3D Computational Fluid Dynamics (CFD) software. The project was performed in the Cooling system
development group at Volvo Cars. First, an analysis of the details of the cooling system and its modelling
theory with 1D CFD models are introduced. Moreover, turbulence and its treatment in 3D CFD are described,
while the theory behind coupling two CFD software is thoroughly established. The method for coupling has
been developed with GT-SUITE for the 1D and STAR-CCM+ for the 3D. The inputs to the system, for
example wall boundaries or operating points, are constant in time. A fully functional co-simulation platform is
tested with different configurations. In each of them, a different component of the cooling system is simulated
in 3D while the rest circuit runs in 1D. The results show stability in the co-simulation of all the configurations
at and near the point that the coupling of the softwares occurs. At next, a discussion is made about the
possible limitations of 1D modeling for these cases, with the conclusion of the advantages that were observed
from the co-simulation in contrast to the extra computational cost it emerged. Lastly, there is an introduction
of cases where cavity or boiling occurs in the cooling system, that require multiphase flow simulations, but
the limitations in coupling the softwares didn’t allow further simulations. An investigation could be further
performed in the future, following the assumption that the software will upgrade their co-simulation capabilities.
Beskrivning
Ämne/nyckelord
Co-simulation , cooling system , coupling , GT-SUITE , 1D CFD , STAR-CCM+ , 3D CFD