Minimal Flow Unit Database of High-Pressure Transcritical Fluid Turbulence

<p dir="ltr">The data corresponds to a direct numerical simulation (DNS) dataset of high-pressure, transcritical turbulent minimal flow unit (MFU) systems using carbon dioxide (CO₂) as the working fluid. This substance is chosen due to its well-documented supercritical behavior, with a critical pressure of 7.4 MPa and a critical temperature of 304.1 K. All simulations are performed at supercritical bulk pressures of 1.5, 2.0, and 5.0 times the critical pressure, covering a range of thermodynamic conditions that traverse the pseudo-boiling regime. The channel geometry features two isothermal walls (a cold wall and a hot wall) separated by a distance of 350 micrometers (channel height), with a half-heigth of delta equal to 175 micrometers. The domain is 2*pi*delta and (2/3)*pi*delta in the streamwise and spanwise directions, respectively<i></i>. Wall temperatures are varied such that the cold wall ranges from 0.8 to 0.95 times the critical temperature, and the hot wall from 1.1 to 1.4 times the critical temperature. These settings are summarized in the dataset configuration table. This thermal setup produces a high-pressure transcritical thermodynamic path across the channel height, crossing the pseudo-boiling line and resulting in sharp gradients in fluid properties and highly nonlinear flow behavior. The flow moves in the streamwise positive direction at a constant bulk velocity of 1.0 meters per second, leading to variable-density turbulence with strong coupling between hydrodynamic and thermodynamic fields.<br><br>The dataset is structured into folders, each corresponding to a specific simulation case. Within each folder, there are 75 instantaneous snapshot HDF5 files (equisdistanced in time) capturing the statistically stationary regime, covering a total of 15 flow through time (FTT) units. Each snapshot includes spatial coordinates (x, y, z) and instantaneous fields such as primitive variables (density rho, velocity components u, v, w, and total energy E), transport properties (dynamic viscosity mu and thermal conductivity kappa), and thermodynamic quantities (pressure P, temperature T, speed of sound sos, specific heat at constant volume c_v, and constant pressure c_p). Statistical data averaged over 15 FTT is stored separately in an HDF5 file.</p>