Function gpu_heat_source 

pub fn gpu_heat_source(
    solver: &mut GpuThermalSolver,
    sources: &[HeatSource],
    dt: f64,
)

Apply volumetric heat sources to the temperature field (mock GPU kernel).

Each source adds source.power * dt to the temperature of its cell.

Arguments

• solver - The thermal solver (updated in place).
• sources - List of heat sources.
• dt - Time step size (s).