"I will contact you to understand the situation that happened yesterday."
In terms of "clarification" with respect to the situation. Not that it can be understood either by one person or the other, but be resolved.
"I will contact you to understand the situation that happened yesterday."
In terms of "clarification" with respect to the situation. Not that it can be understood either by one person or the other, but be resolved.
No, understand is not a verb I would use there.
You say in your final paragraph that the goal is for the situation to be resolved. If you mean you want to reach a final decision and move forward with it, you could say:
I will contact you to resolve the situation that happened yesterday.
If you mean that you want to determine what happened, you could say “clarify the situation” or “ascertain the situation.” Another word that could mean either is “settle the matter.”
Because I like to make my messages short and sweet, I would probably write something like, “I will contact you to find out what happened yesterday,” or “I will contact you to resolve yesterday’s situation.”