CUBENS: A GPU-accelerated high-order solver for wall-bounded flows with non-ideal fluids - presented by M.Sc. Pietro Carlo Boldini

CUBENS: A GPU-accelerated high-order solver for wall-bounded flows with non-ideal fluids

M.Sc. Pietro Carlo Boldini

M.Sc. Pietro Carlo Boldini
Computer Physics Communications Seminar Series
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Computer Physics Communications
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DOI10.52843/cassyni.gwmx6m
Computer Physics Communications
Slide at 02:02
TUDelft P.C. Boldini et al. 1. Introduction: non-ideal compressible fluid dynamics Supercritical heat exchanger Rising interest in non-ideal fluids at supercritical pressure turbomachinery and heat exchangers for higher efficiencies toward decarbonisation Venus atmosphere (97% CO2 at 92 bar) Supercritical fluid region: no phase change failure of the ideal-gas assumption, Z = PROT Supercritical fluid T800 Widom line T360 Z < 0.5 T340 L-like V-like T320 Z < 0.9 0.9 <Z < 0.99 Critical Z> 0.99 point L: liquid T280 (Liquid) T260 Thank V: vapour T240 (Liquid-vapour) from Ren et al., J. Fluid T220 10-1 Mech. 871, (2019) 10-3 10-2 10-1 T,=T*/T Specific volume V* (m³ kg-1) Due to high-density and temperature conditions: experiments are difficult and limited need of high-fidelity simulations CPC 309 (2025) 109507
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References
  • 1.
    J. Ren et al. (2019) Boundary-layer stability of supercritical fluids in the vicinity of the Widom line. Journal of Fluid Mechanics
  • 2.
    P. C. Boldini et al. (2025) CUBENS: A GPU-accelerated high-order solver for wall-bounded flows with non-ideal fluids. Computer Physics Communications
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Summary (AI generated)

There is an increasing interest in non-ideal fluids at supercritical pressures, particularly for applications in turbomachinery and heat exchangers. Operating above the thermodynamic critical point can enhance efficiency and support decarbonization efforts. Supercritical fluids also occur naturally, as seen in the atmosphere of Venus.

To clarify the concept of the supercritical fluid region, we refer to the left plot, which presents reduced pressure against reduced temperature. The critical point is reached when both values equal one. Below this point, a distinct phase change occurs across the saturation line between liquid and vapor. Above the critical point lies the supercritical fluid region, characterized by a continuous transition between liquid-like and vapor-like states, with no phase change occurring along the Widom line.

The right plot illustrates the significant deviation from the ideal gas assumption just above the critical point, as indicated by the low compressibility factor (Z). As we move away from the critical point, particularly at lower pressures, the ideal gas assumption becomes more applicable, with Z approaching unity.

Given this thermodynamic context, conducting experiments, especially for transitional turbulent boundary layers under these conditions, presents considerable challenges. Consequently, there is a pressing need for high-fidelity simulations to enhance and expedite the design of new engineering systems operating under non-ideal gas conditions.

Now, let us examine the existing high-fidelity solvers available for simulating wall-bounded flows. While numerous open-source solvers exist for compressible and incompressible flows, they are primarily developed under the ideal gas assumption. For non-ideal gas conditions, only in-house codes, such as those listed here, are available. Currently, there are no open-source solvers for non-ideal computational fluid dynamics (CFD) in wall-bounded flows.