you need a laser for that... I think....
jets are not really required, just some small holes in a midplate, over the core is what will do the trick. The secret being the channels between the holes in the base plate, giving the incoming stream of cold liquid a way to get out of the way.
My philosophy of using only 2 inlets, and sweeping across the block from one side to the other, is based on the principle of each hole, being a virtual chamber in itself, with 4 little nozzles.... as the channel is much narrower than the diameter of the hole it enters, the turbulence generated by the liquid being squeezed through it are in abundance where I need it most. This is however not how I got to my particular design.... I went about it completely the other way, actually.