Flow around surface-attached multiwall carbon nanotubes was studied using computational fluid dynamics. Two patterns of attachment were examined: nanotubes attached in a straight line and nanotubes attached in a forest formation. Simulations using no-slip and full-slip boundary conditions on the carbon nanotubewater interface were performed in order to compare the two limiting cases of no-slip and complete-slip. Appropriate length and velocity scales were found that can describe the features of the flow. These scales were different than those adopted conventionally for flow around infinite cylinders, and they were used to define a Reynolds number and to develop empirical expressions for the drag coefficient as a function of this Reynolds number.