My problem is that the "open source" definition according to the "Open Source Initiative" requires "no discrimination against persons or group of persons", and by making a difference between academia and non-academia, I can't find an appropiate license model that is "open source" according to the OSI.

Indeed, you've answered the question - you won't find an Open Source licence like this, because it isn't Open Source by definition (Well sure, there's the debate about who gets to define the term, but AIUI, the term "Open Source" was popularied by OSI, and the licences that fit that definition, so it would be best not to potentially mislead people by claiming something is "open source". Saying the code is viewable, available, or whatever as you suggest, seems absolutely fine to me however)

Note that there's also another problem than the discrimination clause - Open Source also requires allowing people to sell the software, so preventing that would be another reason why you won't find an Open Source licence.

That doesn't mean there might not be an off-the-shelf licence that suits your needs, so it is worth asking. Though all the off-the-shelf licences for software that I've seen tend to full under the umbrella of the OSI's or FSF's definitions.

My problem is that the "open source" definition according to the "Open Source Initiative" requires "no discrimination against persons or group of persons", and by making a difference between academia and non-academia, I can't find an appropiate license model that is "open source" according to the OSI.

Indeed, you've answered the question - you won't find an Open Source licence like this, because it isn't Open Source by definition. (Well sure, there's the debate about who gets to define the term, but AIUI, the term "Open Source" was popularied by OSI, and the licences that fit that definition, so it would be best not to potentially mislead people by claiming something is "open source". Saying the code is viewable, available, or whatever as you suggest, seems absolutely fine to me however)

Note that there's also another problem than the discrimination clause - Open Source also requires allowing people to sell the software, so preventing that would be another reason why you won't find an Open Source licence.

That doesn't mean there might not be an off-the-shelf licence that suits your needs, so it is worth asking. Though all the off-the-shelf licences for software that I've seen tend to full under the umbrella of the OSI's or FSF's definitions.