function-pod placement across the k8s cluster

Lets say i 've got a VM cluster with 1 master and 3 worker nodes, where Kubernetes and Openwhisk are hosted.

There is a need to deploy some functions (f1, f2, etc..) in sequence as part of executing a function-workflow (W).
I would like to know if there is a way of forcing in which node each function is going to be placed-executed
e.g f1 on worker2, f2 on worker3

I was thinking about NodeAffinity type of logic but without changing Openwhisk component's source code
Thank you :D