Viscous/inviscid interaction methods employing velocity decomposition have been explored for reducing computational costs in external flow problems. For this, viscous simulations are made in reduced computational domains encompassing the rotational flow region. The coupling of potential and viscous solutions is made on a boundary of negligible vorticity, assessed by means of sampling lines normal to the body wall and the wake. For bluff bodies, sampling lines at the rear tend to be submerged in rotational regions, making it difficult to build the coupling boundary. For overcoming this difficulty, it is proposed in this work to use a transpiration auxiliary surface to represent the influence of the body and the wake. The null vorticity criterion for finding the coupling boundary is also proposed. The proposals are tested for laminar flows around a square, a circular cylinder and a semi-ellipse. The obtained results are compared with those for extended domains. The velocity decomposition with an auxiliary surface is able to reproduce with satisfactory accuracy the flow fields in the reduced domain as well as the drag coefficient on the bodies.

为了减少外部流动问题的计算成本，已经探索了采用速度分解的粘性/无粘性相互作用方法。为此，在包含旋转流区域的简化计算域中进行了粘性模拟。势能溶液和粘性溶液的耦合在可忽略不计的涡度边界上进行，通过与体壁和尾流垂直的采样线进行评估。对于钝体，后部的采样线往往被淹没在旋转区域中，从而难以建立耦合边界。为了克服这个困难，在这项工作中建议使用蒸腾辅助表面来代表身体和尾流的影响。还提出了用于寻找耦合边界的零涡度准则。测试了这些提案的正方形，圆柱体和半椭圆形的层流。将获得的结果与扩展域的结果进行比较。具有辅助表面的速度分解能够以令人满意的精度再现缩小域中的流场以及物体上的阻力系数。