Particle erosion is an ongoing problem in many engineering fields. In this work, a trapezoidal rib installed at different positions on the extrados of a 90 elbow is investigated numerically with the intent of mitigating the erosion. The CFD-DPM Eulerian-Lagrangian approach is employed to evaluate the anti-erosion effect. The computational model is validated by comparing the predicted CFD erosion magnitudes to the present and previous experimental data for a standard elbow. An ellipse erosion zone with a vee-shaped scar is formed on the extrados due to the first and second particle impacts. The rib placed in front of the first impingement can partly protect the elbow from the direct impacts. As a sacrificial element, the rib itself becomes more prone to erosion. A reduction of elbow erosion peak up to 31.4% can be achieved by placing the rib at theta = 25 degrees. However, the erosion resistance is reduced as the rib moves backward. As the flow velocity increases, the sacrificial speed of the rib is accelerated while the anti-erosion effect is weakened. The larger the particle mass loading, the severer the elbow erosion. Taking the sacrificial speed of the rib and the anti-erosion effect into account, placing the rib at theta = 25 degrees is a good choice for such measure. (C) 2017 Elsevier B.V. All rights reserved.