One of the best sonar training targets is a 150 or so pound hog. This is one of the best and most similar to human composition. Of course you may have to get permission to put in a body of water. Most hog farms will donate one if asked. Wire constructed or similar material will produce a target, but if you want to be on target get the pig..the color and shape will be very close to the human..
CFD, what units are you going to use?
Chuck