  The present paper investigates high performance computing abilities of
OpenFOAM for a low Reynolds number ($Re_D=2000$) axisymmetric jet subject to
multiple zero net mass flux (ZNMF) actuators. First, parallel performance of
OpenFOAM is tested by performing a scaling study up to $2048$ processors on a
supercomputer of Flemish Supercomputer Center(VSC). Then, a method to improve
the parallel efficiency is proposed. The method is based on developing a hybrid
concept to calculate the statistical moments. This new concept combines
ensemble and time averaging in order to allow data sampling in parallel. The
motivation is obtaining a reduction in the walltime to collect turbulent
statistics which is observed to be the dominating part in the ZNMF controlled
jet flow. Employing this parallel statistical averaging approach in combination
with regular grid partitioning parallelism, allowed us conducting DNS cases on
$P=624$ processors with an overall speed-up of $S_e=540.56$ and a parallel
efficiency of $E_e=0.87$. The parallelization using only grid partitioning
exhibited inferior performance with $S_e=423.94$ and $E_e=0.68$. In addition to
develop a methodology to increase the parallel performance, we reduced the time
step cost of the existing unsteady solver as well. To this end, an incremental
projection method is implemented into OpenFOAM and a performance gain above
$30\%$ is realized.
