3.1.0.0

Vehicle Speed Calcs
Extra At A Glance ranges
New Driver profile

assets/js/physics.js

@@ -11,7 +11,7 @@
 //    calcConcreteTempPass(arrays...)                        thermal-lag pass over full hourly arrays
 //    calcIndoorTempPass(TaArr, globArr, elevArr, buildingType)  passive indoor temp
 //    calcManagedIndoorTempPass(TaArr, globArr, elevArr, buildingType) managed indoor temp
-//    calcVehicleInteriorTemp(Ta, globalRad, solElev, vehicleType, ventilated)
+//    calcVehicleInteriorTemp(Ta, globalRad, solElev, vehicleType, ventilated, speedMph)
 //    vaporPressureHpa(Ta, RH)              Magnus formula - hPa
 //    solarElevationDeg(lat, lon, dateUTC)  NOAA simplified solar position (-)
 //    calcTmrt(Ta, dirRad, diffRad, globalRad, solElev)  Mean radiant temperature
@@ -396,17 +396,24 @@ export function calcManagedIndoorTempPass(TaArr, globArr, elevArr, buildingType
 //   35-45 -C - dangerous for children/pets (hyperthermia risk)
 //   > 45 -C  - potentially fatal within minutes
 // -------------------------------------------------------------------
-export function calcVehicleInteriorTemp(Ta, globalRad, solElev, vehicleType = 'car', ventilated = false) {
+export function calcVehicleInteriorTemp(Ta, globalRad, solElev, vehicleType = 'car', ventilated = false, speedMph = 0) {
   if (globalRad == null || Ta == null) return null;
 
   // Look up vehicle preset; fall back to a standard car if key unknown.
   const preset = VEHICLE_TYPES[vehicleType] || VEHICLE_TYPES.car;
 
+  // Road speed in m/s. speedMph = 0 is "Static" (parked) and reproduces the
+  // original stationary model exactly; higher speeds scrub the shell with
+  // forced airflow and (windows down) flush the cabin toward ambient.
+  const vMs = Math.max(0, speedMph) * 0.447; // mph -> m/s
+
   // -- 1. Panel conduction ------------------------------------------
   const panelAbsorbed = globalRad * (1 - preset.albedo); // W/m- absorbed by bodywork
-  // Panel surface temp: absorbed solar / convective loss to outside air
-  // hOut ~10 W/m-K (light breeze over panel surface even when parked)
-  const hOut = 10;
+  // Panel surface temp: absorbed solar / convective loss to outside air.
+  // Parked, a light breeze over the panels gives hOut ~10 W/m-K. Once moving,
+  // forced convection rises with road speed (same sqrt form as the surface
+  // model), so the bodywork runs progressively closer to ambient.
+  const hOut = 10 + 5.5 * Math.sqrt(vMs);
   const panelSurfaceTemp = Ta + panelAbsorbed / hOut;
   // Conductive gain into cabin. Cars are thin metal + trim; motorhomes and
   // caravans use insulated sandwich panels, so their bodyU is much lower.
@@ -437,10 +444,14 @@ export function calcVehicleInteriorTemp(Ta, globalRad, solElev, vehicleType = 'c
   const totalGain = conductionGain + glazingGain;
   // Cabin heat rejection: an effective blend of leakage, internal air volume,
   // and surfaces exchanging heat with the outside. With windows open it is
-  // roughly 5- higher - air moves freely
-  // through the cabin, flushing heat out and capping interior temperature much
-  // closer to ambient. Cabin temp still rises a little due to panel/roof solar gain.
-  const effectiveHLoss = ventilated ? preset.hCabinLoss * 5 : preset.hCabinLoss;
+  // roughly 5x higher when parked - air moves freely through the cabin,
+  // flushing heat out and capping interior temperature much closer to ambient.
+  // On the move the through-draught multiplies this further (a 70 mph open
+  // window flushes the cabin almost to ambient). Sealed but moving rejects a
+  // little faster too, because the cooler shell pulls cabin heat out.
+  const speedFactor = 1 + vMs / 12; // grows with road speed (windows-open draught)
+  const lossMult = ventilated ? 5 * speedFactor : 1 + vMs / 40;
+  const effectiveHLoss = preset.hCabinLoss * lossMult;
   const thermalMass = preset.thermalMass ?? 1;
   const solarRise = (totalGain / effectiveHLoss) * thermalMass;
 
@@ -493,30 +504,13 @@ export function calcVehicleInteriorTemp(Ta, globalRad, solElev, vehicleType = 'c
 //
 // -----------------------------------------------------------------------------
 
-// -- FUTURE FEATURE: Vehicle-at-speed thermal model ----------------------------
-// Idea: extend calcVehicleInteriorTemp (or add a companion function) to model
-// cabin temperature for a vehicle travelling at speed, not just parked.
+// -- Vehicle-at-speed thermal model (IMPLEMENTED) ------------------------------
+// calcVehicleInteriorTemp now takes a speedMph argument (Static / 20 / 50 / 70
+// mph in the UI). Forced convection over the shell scales with road speed, and
+// windows-open through-flow scales further with speed, so a moving cabin runs
+// cooler than the same parked car. speedMph = 0 reproduces the static model.
 //
-// Key physics differences from the static model:
-//   - Forced convection over the shell scales with vehicle speed (v-), so
-//     hOut rises significantly - shell cools much faster than when parked.
-//   - Above ~30 mph the vehicle's own forward motion dominates airflow, so
-//     ambient wind direction becomes largely irrelevant (simplifies the model).
-//   - Speed classes to model: urban (~20 mph), dual carriageway (~50 mph),
-//     motorway (~70 mph) - each with a derived hOut multiplier.
-//   - Windows-open behaviour changes completely at speed: at 70 mph open
-//     windows create high-velocity through-flow, dramatically cutting cabin
-//     temp vs. the sealed-car case (but much less pleasant than AC!).
-//   - Roof and bonnet solar gain stays the same; side-glass gain is unchanged.
-//   - AC-off vs AC-on would be the primary user toggle alongside speed class.
-//
-// Suggested signature:
-//   calcVehicleInteriorTempAtSpeed(Ta, globalRad, solElev, vehicleType, speedMph, windowsOpen)
-//
-// This would be a useful companion output column (e.g. "Vehicle (moving)")
-// for road-trip planning, dog-in-car safety at a rest stop vs. motorway, etc.
-//
-// -- CYCLIST AT SPEED (companion to the above) --------------------------------
+// -- CYCLIST AT SPEED (FUTURE) ------------------------------------------------
 // A cyclist generates their own headwind, so the felt temperature (UTCI) is
 // very different from a stationary person - even without ambient wind.
 // Could share the same speed-class approach as the vehicle model: