Something Like This...

I'm scoring a film and I would like to include this effect in my music:

Basically the violas and the cellos play "random" harmonic glissandos on the open fourth string ©, while the basses play a tremolo sul ponticello.

I'm looking for a way to recreate this effect with my sample libraries. I tried using EQs and filters to isolate certain frequencies of a regular note, but it doesn't sound like harmonics at all. I can't find any libraries or synths that inculde this effect or something similar either.

Any suggestions? :)

Find a violist and record him/her.