• Hoverdrop – Leidenfrost Effect physics T-shirt
  • Hoverdrop – Leidenfrost Effect physics T-shirt
  • Hoverdrop – Leidenfrost Effect physics T-shirt
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HoverdropLeidenfrost Effect

Hoverdrop – Leidenfrost Effect Physics T-Shirt

$29.99 USD
$29.99 USD
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Shipping calculated at checkout. Free US shipping · $10 flat shipping outside the US.
Color
White · Black
Size
S–5XL
Made
To order · shipping times

Why does a water drop last longer on a hotter pan? Above roughly 200 °C, the bottom of the drop vaporises at once and the drop floats on its own cushion of vapour. That layer insulates it, so Hoverdrop skates around while drops on a cooler pan boil away quickly. The exact onset temperature depends on the surface. Pixel-art unisex tee; equation, symbols and sources in the physics panel below.

Color
Size

Size guideS–5XL · inches

Details

Size & fitS–5XL

Unisex heavy cotton (Gildan 5000), classic fit.

SizeWidthLengthSleeve
S182815.1
M202916.5
L223018
XL243119.5
2XL263221
3XL283322.4
4XL303423.7
5XL323525

Measurements in inches, ±1.5 in tolerance.

ShippingFree US

Free US shipping · $10 flat shipping outside the US. Printed to order for you.

Delivery times & where we ship

Returns & replacements21 days

Every item is printed to order, so we can’t accept returns or exchanges for change of mind, or if you ordered the wrong size or colour.

Print defect, misprint, damage or the wrong item? We’ll send a free replacement, or a refund if you prefer. Report it within 21 days of delivery with a photo; no need to send it back.

Full refund & replacement policy

The physics

Drop water on a pan at 150 °C and it boils away in seconds. Drop it on a much hotter pan and it skates around for a minute or more.

Above the Leidenfrost point (roughly 200 °C for water on smooth metal, higher on rough surfaces) the bottom of the drop flashes into a thin cushion of vapour. Vapour conducts heat poorly, so the drop is insulated and levitates on its own steam. Johann Gottlob Leidenfrost described it in 1756.

Too hot? Hoverdrop floats.

Equations

\[q = \frac{k_v\,(T_w - T_{\text{sat}})}{e}\]
\[\dot m\,L = q\,A\]
SymbolMeaningUnit
\(q\) heat flux across the vapour film under the drop \(\mathrm{W/m^2}\)
\(k_v\) thermal conductivity of the vapour \(\mathrm{W m^{-1} K^{-1}}\)
\(T_w\) temperature of the hot surface \(\mathrm{K}\)
\(T_{\text{sat}}\) boiling point of the liquid \(\mathrm{K}\)
\(e\) thickness of the vapour film \(\mathrm{m}\)
\(\dot m\) evaporation rate of the drop \(\mathrm{kg/s}\)
\(L\) latent heat of vaporisation \(\mathrm{J/kg}\)
\(A\) area of the drop's base \(\mathrm{m^2}\)

Sources

  1. Quéré (2013) Leidenfrost Dynamics, Annu. Rev. Fluid Mech. 45, 197
  2. Leidenfrost (1756) De Aquae Communis Nonnullis Qualitatibus Tractatus, Duisburg (citation only)
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