Numerical modeling of a four-electrode electrochemical accelerometer based on natural convection: The boussinesq flow model vs. The compressible flow model

Two-dimensional numerical simulations are conducted to study the feasibility of applying the Boussinesq approximation to the steady-state buoyancy-driven flow in a four-electrode electrochemical accelerometer. Two kinds of electrode layouts along the electrochemical cell, the anode-cathode-cathode-anode (ACCA) and the cathode-anode-anode-cathode (CAAC), are examined. The results from the model based on the Boussinesq approximation are compared to those from the compressible flow model. Though the Boussinesq flow model leads to fairly large quantitative deviations, it is capable of qualitatively estimating the output electric current when the output electric current increases linearly as the applied axial acceleration. A qualitative difference between the two models are found in the centerline density profiles in the electrochemical cell, which can be explained by the compressibility-induced acceleration/deceleration. It is found that the Boussinesq approximation is good enough for the estimation of the electric current at a single electrode while can make large deviations of the cathodic current difference, i.e., the output electric current in this study.