I would like to know how to calculate the temperature change of a moving object. For example if I throw a ball that is warmer than the surrounding air, how much would it lose form it's temperature in every second? I searched for two days now, but I have only partial solutions :(. I would need a formula that takes in account the followings:
- The material of the ball (Iron, heat conductivity?)
- Area of the ball
- Speed of the ball (true airspeed)
- Material of the surrounding material (air, heat conductivity?)
- And ofc temperature of the ball and the surrounding material.
- anything else I forgot and neccessary :):)
It dosen't need to take in account friction generated heat and other things, I only need the temperature loss 🙂
Best Answer
If the speed of ball is large most of the time, then speed of air flow across the ball (as seen from reference frame attached to the ball) is large most of the time, which means that heat transfer from ball to air is predominantly due to forced convection rather than free convection. With this assumption, you may use forced convection relations for heat transfer, which depends on air-speed across the ball, surface temperature of the ball, and thermodynamic properties of air. However these relations are empirical and are usually for constant air-speed, while in your case air-speed is changing with time. You may assume some average value of heat transfer coefficient to get an estimate. If thermal conductivity of the ball is high enough that entire ball is nearly at uniform temperature at all times, then you won't have to solve for temperature field inside the ball (to find its surface temperature, which is what is required ultimately). Regarding this last point read up lumped-system analysis and Biot number.