In article ,
Nicolaas Vroom writes:
On Tuesday, 7 November 2017 00:19:18 UTC+1, Phillip Helbig wrote:

You don't need a simulation. There is acceleration if

Omega/2 - lambda 0.

Which are the present values for Omega and Lambda?

Omega = 0.3, lambda = 0.7.

When you visit
https://lambda.gsfc.nasa.gov/toolbox/tb_camb_form.cfm
they use Omega(b), Omega(c), Omega(nu) and Omega(k)
Lambda is not mentioned.

The dynamics of the universe depend on the total value of Omega, dark
matter, baryons, etc. If you're interested in the contents, then it
makes sense to have different symbols, otherwise you have to add them
all up.

In one notation (unfortunately, there are several)

Omega_M + Omega_Lambda + Omega_K = 1

or

Omega + lambda + Omega_L = 1

Hence Omega + lambda = 1 if the universe is flat.

Yes, different notation schemes can be confusing, on the other hand
understanding them can help one learn other things.