These two images show the traditional Krishnan dindu as it is called
These lines merge beautifully at the top giving an altogether different effect.
Kamal patterns in the gaps
Flower patterns and spirals to complete the kolam
The images should be self explanatory. The central pattern is called the Krishnan dindu or Lord Krishna's bolster. After drawing this pattern draw the rhombus design on all four sides. Connect them with set of 4 curved lines and then draw more curved lines in the gaps as shown in the pics.
These lines merge at the top giving a different effect to the kolam. Add lotuses , spirals and flowers to complete the rongoli.