Thermal convection in a rotating spherical gap is investigated using numerical simulations and compared with results of the GeoFlow ISS experiment. To induce convection, a radial buoyancy force field is established by using the dielectrophoretic effect from a high-frequency alternating electric field. Two heating sources are implemented. One source is a temperature difference across the gap and the other is the internal dielectric heating of the working fluid. To distinguish both heating sources a heating parameter, $\lambda$, is introduced that is varied together with the electric Rayleigh number, $L$, and Ekman number, Ek $\approx {10}^{-3}$. The governing thermoelectro hydrodynamic equations are analyzed via a linear stability analysis and by three-dimensional numerical simulations. The results are compared with experimental data of the GeoFlow experiment which show that the threshold of convection and the occurrence of global columnar cells agreed with the theoretical predictions. In addition the observed fluid flow showed non-Gaussian characteristics which are described by the quasinormal approximation. The overall flow phenomena are based on polar plumes and equatorial confined columnar cells and in addition are influenced by internal dielectric heating.

中文翻译：

---

GeoFlow国际空间站（ISS）实验中的旋转球形间隙对流

使用数值模拟研究了旋转球形间隙中的热对流，并将其与GeoFlow ISS实验的结果进行了比较。为了引起对流，利用来自高频交变电场的介电泳效应来建立径向浮力场。实现了两个加热源。一种来源是间隙上的温差，另一种来源是工作流体的内部介电加热。为了区分两个加热源的加热参数，$\lambda$随电瑞利数一起变化 $\mathrm{大号}$和Ekman数Ek $\approx {10}^{-3}$。通过线性稳定性分析和三维数值模拟分析了控制热电流体动力学方程。将结果与GeoFlow实验的实验数据进行比较，结果表明对流阈值和整体柱状细胞的出现与理论预测相符。另外，观察到的流体流表现出非高斯特性，其由准正态近似描述。整体流动现象是基于极羽和赤道封闭的柱状电池，此外还受到内部电介质加热的影响。