Junction to ambient, in one model.

Seven control volumes, one continuous solve.

Each level owns its own boundary conditions and the geometry of what sits inside it. Change a channel width and the effect travels all the way out to plant power, then comes back as a junction temperature.

Pick the rejection path, then let the weather decide the duty.

The plant is where most of the argument about a cooling design actually happens, so it is modeled as a choice rather than a constant. Each option carries its own approach behaviour, its own parasitic power and its own water draw, and every one of them moves with wet bulb and dry bulb through the year.

Economizer duty, by climate.

Free cooling is not a yes or no answer. For a given supply temperature, a site spends the year moving between full economizer, partial economizer with trim, and full mechanical cooling, and the split is what actually sets annual energy and water. Sinkpath runs the design point and then runs the year, and reports both.

Raising facility water supply by a few degrees usually moves a site between these bands more than any component swap does. That trade is the whole point of running the annual split next to the design point instead of after it.

The efficiency numbers, computed rather than quoted.

Each of these comes out of the same solve, so they move together when you change something. PUE on its own hides too much, which is why TUE leads here.

Real hardware, not placeholder properties.

A model is only as good as what you can put into it, so these ship with the tool.

Pressure is modeled, not assumed.

Most thermal tools stop at temperature and let pump power in through a fixed allowance. Sinkpath derives the circuit from architecture and technology, then solves it: one cold plate and one connector pair per chip section at that section's own flow, pipes and manifolds sized to a design velocity, fixed bore components scaling as flow squared.

Six pressure drop model classes are available per component, from a fixed value to a fitted polynomial, a vendor table or Darcy friction. Components you have not characterized report as unmodeled instead of quietly contributing zero.

Temperature is a lifetime, not just a limit.

A design that passes at the junction temperature limit and a design that sits ten degrees below it are not equivalent, and a pass or fail verdict hides the difference. Sinkpath reports the thermal margin at every node and carries it through to device life, so a cooling choice can be argued on expected reliability rather than on headroom alone.

The same treatment applies to the plant. Approach temperatures, economizer hours and compressor lift all move with the weather, so the annual mode split is reported alongside the design point rather than in place of it.

One algorithm, checked branch by branch.

The same generic solver runs every case, with no per paper calibration and no fitted constants. Each benchmark states which values were fed and which were predicted, shows the substituted arithmetic step by step, and reports error per row with a group RMSE. Falsification cases run alongside: deliberately wrong modeling assumptions are checked to confirm they miss by margins the correct model does not.

Some branches are finished and some are still running. The table says which is which, because a validation table that only lists wins is not a validation table.

What is anchored, and what is not.

Modeling tools tend to claim every technology equally. These four legs are not equally supported, so here is the honest version.

Two findings from that work changed the model itself. In single-phase immersion the fluid heat up resistance belongs at the tank boundary rather than stacked on the local heat transfer coefficient, and stacking it misses by a factor of fifteen. A case to fluid resistance quoted without its reference temperature is ambiguous by up to 39 percent at low flow, so every resistance reported here names inlet, bulk mean or outlet.

Built inside a thermofluidics research group.