Thermal characteristics of time-periodic electroosmotic flow are analyzed in a micro-annulus under the influence of various alternating electric fields. Representative hydrodynamic and thermal quantities, i.e. volumetric flow rate and Nusselt number, demonstrate oscillatory behaviors approaching a quasi-steady state if few periods of time elapse. An important parameter named dimensionless frequency, which normally affects the diffusion mechanism, is responsible for the penetration depth of momentum and energy into the fluid in the radial direction. The higher the dimensionless frequency, the smaller the transport phenomena diffuse radially into the bulk fluid; while the advection mechanism is intensified and consequently Nusselt number is increased. The cooling-mode mean Nusselt number is slightly smaller than the heating- mode one. A variety of waveforms is examined in the present research; their performances are then compared together using proper measures. A strength index is introduced to evaluate the relative ability of each individual excitation in a half period of time. A key parameter named thermal/frictional index is also utilized to assess the total effectiveness of the system in different circumstances especially when the basic excitation functions are applied. Unlike the vigorous square waveform, the sawtooth one is the most efficient.

在各种交变电场的影响下，在微环空中分析了周期性电渗流的热特性。代表性的流体动力和热量，即体积流量和Nusselt数，表明经过短时间周期后，振荡行为接近准稳态。一个重要的参数，称为无量纲频率，通常会影响扩散机制，它是动量和能量在径向方向上渗透到流体中的深度的原因。无量纲频率越高，沿径向扩散到本体流体中的传输现象越小；同时增加了对流机制，从而增加了Nusselt数。冷却模式平均努塞尔数略小于加热模式之一。在本研究中，研究了各种波形。然后使用适当的方法将它们的性能进行比较。引入强度指数以评估每个单独的激励在半段时间内的相对能力。关键参数称为热/摩擦指数也用于评估系统在不同情况下的总体有效性，尤其是在应用基本激励函数时。与剧烈的方波不同，锯齿波效率最高。关键参数称为热/摩擦指数也用于评估系统在不同情况下的总体有效性，尤其是在应用基本激励函数时。与剧烈的方波不同，锯齿波效率最高。关键参数称为热/摩擦指数也用于评估系统在不同情况下的总体有效性，尤其是在应用基本激励函数时。与剧烈的方波不同，锯齿波效率最高。