Academic name for graphs which curve like a bridge

Question

These are the images of the graphs I want to know the academic names:

I've googled and learnt that their names are Concave Down Curve and Concave Up Curve. However, I want to know if there are any other names for these graphs as I want to use them in a sentence like:

"The sales from 2011 to 2017 resembles a concave down curve with the lowest point being 2015 at 20,356 sales"

Edit 1: Guys, thank you for your inputs.
However, my question was not that related to math, but was to find a good descriptive sentence for my IELTS writing. Here is the graph I came across in the test:

I noticed that, as people get older, women tend to do more exercises, and then less, their trend shapes like a bridge, while a reversion of that can be seen in men. Now, if I were to compare these two trends while trying to sound academic, should I write something similar to the following?

"A demographic trend which resembles a concave down curve can be seen in women's figures while it is the opposite for men's"

Could you guys give me a more well structured and better sentence without sacrificing the "concave down curve or u-shaped curve" because I really want to include those terms.

user1661469 · Answer

This being sales data and not a pure function, I wouldn't advise using an academic description. I'd expect sales data at a micro-level to move in a geometric manner, due to the nature of communication. The example graphs look polynomial.

If I were instructing someone to draw this graph, I would tell them to draw a parabola whose endpoints approach positive/negative infinity.

Referring to the "low point," I'd call it this valley's local minimum. Unless it was the lowest point in the range, which would be the absolute minimum.

user250338 · Answer

Looking at the shape of your graphs, it is best to simply say that the percentage for women increases and then decreases, while that for men decreases and then increases.

Barmar · Answer

The phrase I've seen for the first curve is "Inverted-U Function". Examples are:

Inverted-U Hypothesis
Inverted-U Function

And the second graph is called a "U-Curve":

Midlife Crisis? Or Just Bottoming Out on the U-Curve of Happiness
Happiness, stress, and age: How the U-curve varies across people and places

Randy Kennedy · Answer

The curve is called a 'catenary', the curve of a cable or chain suspended at two points, while under the influence of gravity.

https://physics.stackexchange.com/questions/64240/why-wont-a-tight-cable-ever-be-fully-straight

Chung David · Answer

Positive convexity means concave up. Negative convexity means concave down. The positive and negative refer to the positive/negative value of the rate of change of the function f'. (To understand the meaning rate of change you need to at least do Calculus 1)
It is a commonly used term in finance.
See definitions below:
Investopedia: Convexity
Corporate Finance Institute: Negative Convexity.

Academic name for graphs which curve like a bridge

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