How to include material properties to the database if the % of mixtures are known
 

Hi CFD community,

First off , a little bit about what I'm going to achieve with the simulation. I'm doing a steady state CFD analysis on a straight tube compact HX(Automotive radiator). My primary goal is to align my results with a journal paper i downloaded on this topic. The problem i am facing is the author says he inputs 75% water and 25% ethylene glycol (I'm sure both materials are present within the comprehensive library). So the first question I want to ask is how can i create a custom material whose percentage values are known.

The second question i stumbled upon is , In the journal the author sets the zone temp to 368K which itself is the incoming coolant temperature. Is it correct to take that assumption? Well I'm thinking about giving the zone temp rather lower value than the inlet temp and inlet temp as 368K. I attached the model geometry . I have also issues with the application of convective wall BCs, because the author explicitly doesn't mention of it, which i presume is manageable at this point. Pls share your thoughts on the issues I raised.
Thank you

Vishnu R