|This paper presents the results of a study the authors conducted to identify the opportunities and challenges of interfacing complex engineering simulations run on dedicated systems with mobile devices visualizing the simulation results and providing inputs in real-time. We build upon an existing finite element method (FEM) simulation, which we tuned to deliver snapshots to an Augmented Reality (AR) application for real-time visualization. On this basis we develop interaction designs for tablets and Optical See-Through Head-Mounted Displays (OST-HMD) utilizing the interaction methods available on such mobile devices to manipulate FEM simulated tubes in AR, as well as an evaluation of these interaction designs. Our design goal is an intuitive workflow concept that allows usage of an AR application without training overhead. To this end we introduce movable proxies on the virtual tube that provide the simulation with input data. Since the described client devices belong to very different device classes, we show intuitive interaction designs for all of them. Our client application is supposed to be run at the tube installation site, so we can not rely on stable high bandwidth connections to the simulation server in every case. Therefore, we implemented an asynchronous communication, enabling the use with reduced update rates. Our system enables the user to quickly reconfigure tube configurations and compare different approaches. At the same time the interaction is intuitive so training the user is unnecessary.