The ornamental design for a movablefan, as shown and described.
1. Movable fan
1.1 : Perspective
1.2 : Front
1.3 : Back
1.4 : Left
1.5 : Right
1.6 : Top
1.7 : Bottom
1.8 : Reference
1.9 : Reference
1.10 : Reference
1.11 : Reference
Reproductions 1.8 and 1.9 are reference view showing the state that the fan head on the top is lifted, pulled and rotated 360 degrees; the broken line showing of a driving robot module in reproductions 1.10 and 1.11 are included for the purpose of illustrating environment of the moveable fan and forms no part of the claimed design.