You can use set analysis to accomplish this. What you will need to know is what "today" constitutes to determine yesterday.
Does "today" mean the actual current day, regardless of the data model? In that case, you could create a variable for yesterday like so:
This will be in numeric format. If you need it as a date string, you can wrap it in date():
Alternatively, "today" might just mean the most recent date available in your data or subset of data selected. To calculate this, you will need to take the max of your date field:
Now that you have determined the correct day and stored it in a variable, you can use set analysis in the expression you want to limit to yesterday. The expression would look like this:
What this does it tell QlikView to calculate the sum of Expression1 where your DateField is equal to the value stored in vYesterday.