rack solves a reduced thermal and hydraulic model in your browser. It is for comparing layouts and finding capacity pinch points, not for sign-off.
What the solver does
- Thermal: transient lumped RC nodes for each rack, the mixed coolant volume and room air. Electrical IT load enters as heat; each heat path is accounted for in the energy balance.
- Hydraulics: one equivalent water loop. Darcy–Weisbach pipe loss and a quadratic pump curve set flow; each rack branch receives an equal share. Water in and out have equal mass flow.
- Room air: a mixed-air node with user-set supply temperature and ventilation mass flow. The view shows circulation direction, not a CFD velocity field.
- Time: explicit 0.5 s integration steps, advanced at 5× wall-clock speed in a Web Worker. Rendering runs separately.
Inputs and uncertainty
CoolantSingle-phase waterρ 997 kg/m³ · cp 4,180 J/kg·K · μ 0.89 mPa·s
Rack heat capacity5 MJ/K per racklumped estimate; varies by build and operating state
Rack-to-coolant UA28 kW/Kestimated conductance; editable in the scenario file
Air-side conductance0.75 kW/K per racksimplified convection; bypass and recirculation are not resolved
Pipe network18 m · 55 mm · K = 25estimated equivalent circuit; fittings are grouped into K
CDU and pump500 kW · 600 L/mineditable nameplate estimates, not vendor selections
Published hardware references
The solver uses the first pump/CDU pair that shares a connected component with a rack. Other circuits stay visible but are not simulated. The NVIDIA shelf rating is not an operating IT load. AMD does not publish a rack input-power figure on the cited Helios overview. Both rack workload power values in this scene are editable estimates. Component geometry is illustrative.