Dumitru, Andrei N (2025), A Different Approach to the Dynamo Mechanism, Cunoașterea Științifică, 4:3, 57-64, DOI: 10.58679/CS88989, https://www.cunoasterea.ro/a-different-approach-to-the-dynamo-mechanism/

 

Abstract

The study of the Earth’s magnetic field is the subject of a continuous and complex research effort. Practically, almost all studies on the geomagnetic field are based on the heat provided by the inner core. Other sources of heat are also invoked, such as the decay of radioactive elements, gravitational force, chemical reactions. However, solutions are still sought for a coherent understanding of the geodynamo mechanism that leads to the generation of the Earth’s magnetic field in the rotating fluid outer core and good conductor of electricity. After studying the elements that participate in the operation of the dynamo mechanism through the prism of the basic principles of physics, an operating model was found that provides a coherent understanding of the geodynamo, based on the phenomena that occur at the place of contact between the lower mantle and the outer core. At the same time, this model reconfirms and consolidates the dynamo theory formulated by Sir Edward Crisp Bullard.

Keywords: Dynamo Mechanism, Inner-core, Outer-core, Friction, Heat, Static electricity

O abordare diferită a mecanismului Dinamo

Rezumat

Studiul câmpului magnetic al Pământului face obiectul unui efort de cercetare continuu și complex. Practic, aproape toate studiile asupra câmpului geomagnetic se bazează pe căldura furnizată de nucleul interior. Sunt invocate și alte surse de căldură, cum ar fi dezintegrarea elementelor radioactive, forța gravitațională, reacțiile chimice. Cu toate acestea, se caută încă soluții pentru o înțelegere coerentă a mecanismului geodinamo care duce la generarea câmpului magnetic al Pământului în nucleul exterior fluid, rotativ și bun conducator de electricitate. După studierea elementelor care participă la funcționarea mecanismului dinamo prin prisma principiilor de bază ale fizicii, s-a găsit un model de funcționare care oferă o înțelegere coerentă a geodinamo, pe baza fenomenelor care apar la locul de contact dintre mantaua inferioară și nucleul exterior. În același timp, acest model reconfirmă și consolidează teoria dinamo formulată de Sir Edward Crisp Bullard.

Cuvinte cheie: Mecanismul Dinamo, nucleul interior, nucleul exterior, frecare, căldură, electricitate statică

 

CUNOAȘTEREA ȘTIINȚIFICĂ, Volumul 4, Numărul 3, Septembrie 2025, pp. 57-64
ISSN 2821 – 8086, ISSN – L 2821 – 8086, DOI: 10.58679/CS88989
URL: https://www.cunoasterea.ro/a-different-approach-to-the-dynamo-mechanism/
© 2025 Andrei N DUMITRU. Responsabilitatea conținutului, interpretărilor și opiniilor exprimate revine exclusiv autorilor.

 

A Different Approach to the Dynamo Mechanism

Andrei N DUMITRU[1], MPhil
dumitru.andrei@vivascience.org.ro

[1] Independent researcher, ORCID ID: 0009-0004-4069-397X

 

Introduction

“A fundamental goal of geophysics is a coherent understanding of the geodynamo”

Credit: Gary A. Glatzmaier, 1995).

 

The Earth’s magnetic field is studied extensively, with the dynamo theory by Sir Edward Crisp Bullard being widely accepted but missing how it works. Three conditions are considered necessary for dynamo mechanism: an electrically conductive fluid, kinetic energy, and an internal thermal energy source to fuel convection in the outer core (OC). While the first condition has been met, the origins of both kinetic energy and internal thermal energy remain ambiguous.

Is Inner core the main source of heat for convection currents?

Glatzmaier and Roberts (1995) estimated that the Earth’s magnetic energy is about 4,000 times greater than the kinetic energy of the convection responsible for maintaining it but did not explain this difference. Meanwhile, a good question is what heats the solid IC at around 5,000 K to warm the OC at around 3,000 K? IC’s heat is attributed to residual heat from Earth’s formation, gravitational compression, radioactive decay. This heat then transfers outward to the OC, which remains liquid due to lower pressure. However, these alleged sources invoked for the heating of the IC are practically impossible to assess if, and in what proportions, they contribute to the constant maintenance of the IC at a given temperature level.

There is a paradox here: although OC and IC have a similar composition and are not separated adiabat, IC accumulates and constantly maintains a significantly greater amount of heat than that existing in OC. However, after more than 4 billion years at least one principle of thermodynamics – if not all of them – in Earth’s case does not work?

Therefore, IC cannot be the main source of heat for convection currents.

Thermal energy and  electric energy

Many self-consistent convection-driven dynamo models have been developed, too. Examples: Glatzmaier and Roberts 1995; Chan et al. 2007; Chan et al. 2008. Almost all such studies end up considering the solid IC as the main source of heat for convection currents inside OC.

Thorne Lay et al. 2008 considered that Earth functions as a large heat engine driven by various sources. Chan et al. 2008 observed that: (i) the electrically heterogeneous lower mantle can induce an oscillating dynamo; (ii) the outer core, where convective motions generate magnetic fields, is somehow thermally or electrically coupled to the heterogeneous lower mantle as an inseparable part of the dynamo system. Love, J.J. & Swidinsky A. 2015 remark: (i) “…in general, when the geomagnetic field is active, so is the geoelectric field”  and (ii) “…galvanic distortion … is, sometime, attributed to the quasi-static accumulation of electric charges along the boundaries of spatial heterogeneities in lithospheric conductivity and within conductivity gradients.”  And Glyn A. Collinson et al. 2024 confirmed a 60-year-old hypothesis about Earth’s ambipolar electrostatic field.

Studies have explored the relationship between the OC surface flow, lower mantle, and Earth’s magnetic field. R. Hide 1969 suggested that the Earth’s mantle precessional motion could influence OC fluid dynamics generating the magnetic field. D. Jault 1988 found differential zonal rotation of the OC fluid at the Core-Mantle Boundary (CMB), symmetrical to the Equator. Glatzmaier and Roberts 1995 estimated OC velocity at a maximum of 0.4 cm/s. R. Hide et al. 1998 confirmed the differential rotation of the Earth’s OC. Jackson 2003, I. Wardinski 2020 observed a nonaxisymmetric magnetic flux moving westward in the equatorial belt zone. Gauthier Hulot and Celine Eymin 2005 examined core surface flows using satellite data. Stefan Maus et al. 2008 questioned if OC’s surface flow models can enhance Earth’s magnetic field forecasts considering that OC’s typical velocities are of the order of tens of kilometers per year. Buffett 2014 suggested that geomagnetic fluctuations show stable stratification at the top of the Earth’s core, with an estimated heat flow of approximately 13 terawatts. I. Wardinski 2020 modeled the OC’s magnetic field and its secular variation.

There are also studies approaching IC movement. For example:  Glatzmaier 1995, Song 2023, Wei Wang 2024. Wei Wang et al. 2024 reported super-rotation stabilization rate at 0.05-0.15 degrees/year.

All studies observe the mobility of IC, OC and mantle, where the rotating mantle constitutes the only constant source of kinetic energy.

The model

The scientific community assumes that initial temperature generated at the formation of the planet, gravitational compression on the core, decay of the radioactive elements, solidification of the inner core, chemical reactions are the main sources of heat inside the Earth.

However, these sources are not permanent and/or sufficient to produce the heat necessary for convective currents to generate and maintain the Earth’s magnetic field. Thus, how much can we count on the initial temperature of the planet after more than 4 billion years? The role of gravitational compression in heating the nucleus is questionable because it does not explain contradictory effects such as the large temperature difference between IC and OC nor the low viscosity and high velocity of OC. As for radioactive decay, it is assumed that in the mantle and nucleus there would be uranium, thorium and potassium -40 dispersed in relatively small quantities. By decay, it could not produce significant thermal effects. However, radioactive decay is a spontaneous process, dependent on the environment in which it occurs (core, mantle, pressure, depth, temperature). In conclusion, radioactive decay cannot be a permanent and stable source of heat. And the heat transfer from IC to OC due to IC solidification directly opposes gravitational compression effects.

The constant source of both thermal energy and static electricity

The mantle’s linear rotation speed at the CMB equator is 252 m/s. Due to inertia, the rotation speed of the OC’s surface flow is lower than that of the mantle. This differential generates heat and static electricity due to friction over an area of 1.51619421 × 10¹⁴ m².

As for IC, seismograms have shown that the IC can rotate or move in any direction relative to the mantle Wei Wang 2024. Friction between the solid IC and the fluid OC also generates heat and static electricity over an area of 2.0302187 × 10¹³ m². The  position of the IC is not rigid, so that it can move in any direction inside OC due to its own mass influenced by kinetic factors like Earth’s rotation, Earth’s gravity, lunar and solar gravitational forces, Coriolis forces and OC convection currents.

Static electricity typically arises from the triboelectric effect, where charges accumulate on objects. Within OC conductive fluid, heat and static electricity are transferred through a continuous tribodynamic process that spans billions of years, reaching from the core-mantle boundary (CMB) to the inner core (IC) and back. This process generates convection currents that sustain Earth’s geomagnetic field. Variations in structure, density, and temperature between the outer core and mantle facilitate the dissipation of heat and electrostatic energy towards upper layers (Glatzmaier and Roberts 1995; Love, J.J. & Swidinsky A. 2015; Shuaihang Pan 2019; Guangming Liu et al. 2022).

Results and discussion

This dynamo model shows that Earth functions like a thermoelectric capacitor, powered by an internal tribodynamic device and by solar energy as it is suggested by obvious analogies.

The heat generated in the core is conserved in storage capacities such as the mantle, crust, oceans and atmosphere, and geothermal processes follow the principles of thermodynamics.

The function of an electric capacitor, namely the storage of static electricity, is achieved by the same capacities related to heat, but it is subject to the laws of electrodynamics. The existence of this function is confirmed by Earth’s ambipolar electrostatic field, geomagnetic field and electromagnetic phenomena from deep Earth up to outer space.

Conclusions

This dynamo mechanism offers a coherent understanding of the geodynamo. new explanations regarding the geomagnetic field, the geoelectric field and the related phenomenology not only for planet Earth, but also for any rotating celestial body.

It can also foster advances in aerospace industry, space exploration,  geothermal fenomena, weather forecasts.

Abreviations

CMB: Core-Mantle Boundary; IC: Inner Core; OC: Outer-Core

Acknowledgements

The author would like to record his gratitude to scientists whose research led to the design of the dynamo mechanism presented in this paper.

Author’s contribution

The manuscript was organized using the author’s study of the cited papers. Partially translated from Romanian to English with AI aid.

Funding

Own funds.

Credit authorship statement

The author wrote the entire original draft.

Competing interests

The author declares that he has no competing interests.

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