Self-Excited Dynamo Driven by Non-Rotating Laminar Thermal Convection in a Regular Tetrahedron

Abstract: We propose a minimal, rotation-free model of magnetohydrodynamic (MHD) dynamo action driven by laminar thermal convection in a regular tetrahedral cavity. Unlike canonical planetary-dynamo settings, where flow helicity is supplied by global rotation, the present system generates robust flow helicity purely through the geometric constraints imposed by tetrahedral boundaries. Direct numerical simulations show exponential amplification of a weak seed magnetic field and a nonlinear saturated state in which the magnetic energy exceeds the kinetic energy. The convective flow organizes into a highly symmetric pattern with (D_4) dihedral symmetry. The dynamo-generated magnetic field obeys a corresponding signed (D_4) symmetry involving antisymmetry under (π)-rotations about the two horizontal axes of the tetrahedron. The tetrahedral dynamo provides a conceptually transparent setting for isolating geometry-induced helicity, magnetic-field amplification, and a closed induction cycle in a non-rotating laminar flow.