Is there a figurative phrase for "ashamed" to mean to bend your head downward or look down, as you can't look at others?
In Persian we say سر افکنده which almost means Head Down, or Head fallen
There's a similar expression in english - to hang your head (in shame). It has very much the same meaning as the expressions you mention.
Hang one's head: let one's head fall forward (e.g., when ashamed)
For example:
When I was caught cheating in the exam, I hung my head in shame.
Athletes caught taking drugs should hang their heads in shame.
The defendant hung his head in shame.
We also say that a person
couldn't look [someone] in the eye/face
when they are ashamed (often because they are lying, but not always). This is pretty much a set phrase, so it's often singular eye instead of plural eyes.
From Collins Dictionary:
to look someone in the eye
or look sb in the face
phraseIf you look someone in the eye or look them in the face, you look straight at their eyes in a bold and open way, for example in order to make them realize that you are telling the truth.
He could not look her in the eye.
Crestfallen (or maybe downcast) might be another single word equivalent. Crest in English refers to the head or top of something; so the word directly connotes the head being down, but means being sad or disappointed (whether because of shame/embarrassment or any other reason).
crest·fal·len
ˈkres(t)ˌfôlən/
adjective
adjective: crestfallen
sad and disappointed.
"he came back empty-handed and crestfallen"
synonyms: downhearted, downcast, despondent, disappointed, disconsolate, disheartened, discouraged, dispirited, dejected, depressed, desolate, in the doldrums, sad, glum, gloomy, dismayed, doleful, miserable, unhappy, woebegone, forlorn; More
antonyms: cheerful
Origin
late 16th century: figuratively, from the original use referring to a mammal or bird having a fallen or drooping crest.
In addition to:
hang your head in shame
we also might use:
shamefaced, tail between his legs
shame·faced ˈSHāmfāst/ adjective feeling or expressing shame or embarrassment. "all the boys looked shamefaced" synonyms: ashamed, abashed, sheepish, guilty, conscience-stricken, guilt-ridden, contrite, sorry, remorseful, repentant, penitent, regretful, rueful, apologetic; embarrassed, mortified, red-faced, chagrined, humiliated;
informal: with one's tail between one's legs "Giles looked shamefaced"
Google Dictionary
Bow/hang your head in shame. http://www.macmillandictionary.com/dictionary/british/shame_1 Hope this helps
I have heard and read of a hangdog look or expression.
Per: Dictionary.com
shamefaced; guilty: He sneaked out of the room with a hangdog expression.