Dynamo power budgets and competing scaling laws
Research context
research method · conditional · As of 2026-10-10
A statistically steady dynamo with no net mechanical or Poynting power through its boundary balances supplied buoyancy power against ohmic and viscous dissipation.
Key knowledge
A statistically steady dynamo with no net mechanical or Poynting power through its boundary balances supplied buoyancy power against ohmic and viscous dissipation. Power-based field scalings rely on regime and length-scale assumptions; similar large-scale fields do not determine one unique force balance or core flow.
Values and equations
P = D_ohm + D_visc; D_ohm = integral (η_m/μ0) |curl B|^2 dV
- P
- Supplied buoyancy power W
- D_ohm, D_visc
- Ohmic and viscous dissipation W
- η_m
- Magnetic diffusivity m^2 s^-1
- μ0
- Magnetic permeability H m^-1
- B
- Magnetic flux density T
Conditions and scope
- Time averages must span relevant variability. Nonzero net mechanical or Poynting boundary power requires an explicit additional term in the energy budget.
- Distinguish tested numerical trends from extrapolation to far smaller planetary diffusivities.
- Statistically steady time-averaged kinetic and magnetic energies, with no net mechanical/Poynting boundary-power flux and no other omitted power source. Otherwise retain those contributions explicitly.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Predictive scaling laws for spherical rotating dynamos: Section 3: time-averaged power and ohmic/viscous dissipation (selected source body inspected).
2026-10-10 · Bounded source check of the recorded statement and conditions. This does not certify a unique physical model, reproduce the cited study or replace independent branch review.
Entry details
Permanent link to this entry ↗- Record identity
- research-earth-dynamo-power
- Revision
- research.1
- Structured reference record
- Postgraduate & research reference