Field Notes on CoolSim | SaaS CFD for Data Center Airflow & Thermal Optimization

What is CFD?

Tue, 22 Jul 2025 12:26:30 -0400

Computational fluid dynamics (CFD) computes how air, heat and pressure move through a space by solving the equations of fluid flow on a computer. For a data center, that turns questions like Will this row run hot if a cooling unit fails? or How much of our cooling is reaching the racks? into questions you can ask of a model instead of the room.

The governing equations

Fluid flow is governed by three conservation laws: mass cannot appear or disappear, force equals the rate of change of momentum, and energy is conserved. Together they are usually called the Navier–Stokes equations.

Key Data Center Cooling Metrics

Mon, 28 Apr 2025 13:12:01 +0000

An operator usually wants two things from a data hall: equipment that gets air it can use, and a cooling bill that isn’t larger than it needs to be. Three metrics each answer part of that.

Power Usage Effectiveness (PUE) measures the energy the whole facility spends on top of its IT load.
Rack Cooling Index (RCI) measures how many equipment intakes sit outside the ASHRAE temperature range, and by how much.
Return Temperature Index (RTI) measures whether the cooling units move more or less air than the equipment draws.

None of the three is enough on its own. This article defines each one, works an example, and says what each leaves out.

The Evolution of Data Center Design

Mon, 28 Apr 2025 13:12:01 +0000

Each generation of data hall was laid out to fix the airflow problems of the one before it. The question behind every layout is the same: does the cold air reach the rack intakes, and does the hot air get back to the cooling units without mixing on the way?

This article follows three layouts, from the enterprise raised floor to the fan-wall hall, through a CoolSim model of each, and looks at what each model shows. The metrics quoted are the ones in the CoolSim report, explained in Key Data Center Cooling Metrics.