Steady geotherm with internal heat production
With depthz positive downward, constant conductivityk and uniform volumetric heat productionH, a stationary conductive slab obeys kT_zz+H=0.
Key knowledge
With depthz positive downward, constant conductivityk and uniform volumetric heat productionH, a stationary conductive slab obeys kT_zz+H=0. If T(0)=T_s and outward/upward surface heat flux is q_s=kT_z(0), then T(z)=T_s+(q_s/k)z−Hz²/(2k). At H=0 the gradient is constant; internal production makes upward flux decrease with depth in this model.
Values and equations
kT_zz+H=0; T(z)=T_s+(q_s/k)z−Hz²/(2k); q_up(z)=q_s−Hz
- T,T_s
- slab and surface temperatures K
- z
- depth positive downward m
- k
- thermal conductivity W m⁻¹ K⁻¹
- H
- uniform volumetric heat production W m⁻³
- q_s,q_up
- surface and depth-specific upward heat flux W m⁻²
Conditions and scope
- k>0, finite stationary slab, constant H, no advection or phase change, and surface plus basal boundary conditions consistent with the chosenq_s. Positive outward flux means heat flows toward shallowerz.
- H(z),variablek and transient or advective regimes require another solution. Measured gradient and surface heat flow do not uniquely separate basal heat supply, conductivity and radiogenic production; not every geotherm is linear.
Sources · 1
References
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Evidence and review
Read inspected control-volume energy balance and explicit statement that radiogenic production is omitted in Lecture13, plus its H=0 steady geotherm. Added H as an openly disclosed conservation source, integrated the constant-H ODE twice and verified surface flux/sign; this heat-production extension is derived, not attributed as a printed source formula.
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Entry details
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