It is very important to check that the Auto Constraints feature is turned on before creating any sketches in DesignModeler. Otherwise, vertices and lines in your sketches will not be coincident with the coordinate axes. This can cause problems in your solution later on. The Auto Constraint feature is not turned on by default in ANSYS 15.0. This tip demonstrates how to turn on the Auto Constraint feature in DesignModeler.
Before creating a sketch, click on the "sketching" tab.
Next, click on Contraints and keep scrolling untill Auto Contraints appear.
Finally, click on Auto Contraints and check the boxes next to Global and Cursor.
Okay, all set! Have fun sketching and modelling!