Highlights  A detailed literature review of outdoor ventilation studies performed with CFD is presented.  This review shows a lack of studies for generic urban configurations with unequal street widths.  Here: new CFD simulations for generic configurations with equal and unequal street widths  For most wind directions, the main street is generally beneficial for ventilation of downstream region.  For wind parallel to main street, main street is generally not beneficial for ventilation of downstream region.